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The Objective Caml system release 3.08

1. The initial 0 is the digit zero the 0 for octal is the letter O The interpretation of integer literals that fall outside the range of representable integer values is undefined For convenience and readability underscore characters _ are accepted and ignored within integer literals Floating point literals float literal 0 9 0 9 _ 0 9 _ e E 0 9 0 9 _ Floating point decimals consist in an integer part a decimal part and an exponent part The integer part is a sequence of one or more digits optionally preceded by a minus sign The decimal part is a decimal point followed by zero one or more digits The exponent part is the character e or E followed by an optional or sign followed by one or more digits The decimal part or the exponent part can be omitted but not both to avoid ambiguity with integer literals The interpretation of floating point literals that fall outside the range of representable floating point values is undefined For convenience and readability underscore characters floating point literals are accepted and ignored within Chapter 6 The Objective Caml language 93 Character literals gt regular char gt escape sequence ee n t b r oo 0 pers ee A Fla 0 9 A Fla char literal escape sequence R x 0 9 Character literals are delimited by single quote characters The two single quot
2. bool gt bool gt bool The boolean or Evaluation is sequential left to right in e1 e2 e1 is evaluated first and if it returns true e2 is not evaluated at all val or bool gt bool gt bool Deprecated Pervasives should be used instead Integer arithmetic Integers are 31 bits wide or 63 bits on 64 bit processors All operations are taken modulo 231 or 2 3 They do not fail on overflow val int gt int Unary negation You can also write e instead of e val succ int gt int succ xis xtl val pred int gt int pred x is x 1 val int gt int gt int Integer addition val int gt int gt int Integer subtraction val int gt int gt int Integer multiplication val int gt int gt int Integer division Raise Division_by_zero if the second argument is 0 Integer division rounds the real quotient of its arguments towards zero More precisely if x gt 0 and y gt 0 x y is the greatest integer less than or equal to the real quotient of x by y Moreover Cx y x y y val mod int gt int gt int Integer remainder If y is not zero the result of x mod y satisfies the following properties x x y y x mod yand abs x mod y lt abs y 1 Ify 0 x mod y raises Division_by_zero Notice that x mod y is negative if and only if x lt 0 val abs int gt int Chapter 19 The core library
3. val to_float int64 gt float Convert the given 64 bit integer to a floating point number val of_int32 int32 gt int64 Convert the given 32 bit integer type int32 to a 64 bit integer type int64 val to_int32 int64 gt int32 Convert the given 64 bit integer type int64 to a 32 bit integer type int32 The 64 bit integer is taken modulo 282 i e the top 32 bits are lost during the conversion val of_nativeint nativeint gt int64 Convert the given native integer type nativeint to a 64 bit integer type int64 val to_nativeint int64 gt nativeint Convert the given 64 bit integer type int64 to a native integer On 32 bit platforms the 64 bit integer is taken modulo 2 On 64 bit platforms the conversion is exact val of_string string gt int64 Convert the given string to a 64 bit integer The string is read in decimal by default or in hexadecimal octal or binary if the string begins with Ox Oo or Ob respectively Raise Failure int_of_string if the given string is not a valid representation of an integer or if the integer represented exceeds the range of integers representable in type int64 val to_string int64 gt string Return the string representation of its argument in decimal val bits_of_float float gt int64 Return the internal representation of the given float according to the IEEE 754 floating point double format bit layout Bit 63 of the result represents the
4. NI_NOFQDN Do not qualify local host names NI_NUMERICHOST Always return host as IP address NI_NAMEREQD Fail if host name cannot be determined NI_NUMERICSERV Always return service as port number NI_DGRAM Consider the service as UDP based instead of the default TCP Options to Unix getnameinfo val getnameinfo sockaddr gt getnameinfo_option list gt name_info getnameinfo addr opts returns the host name and service name corresponding to the socket address addr opts is a possibly empty list of options that governs how these names are obtained Raise Not_found if an error occurs Terminal interface The following functions implement the POSIX standard terminal interface They provide control over asynchronous communication ports and pseudo terminals Refer to the termios man page for a complete description type terminal_io mutable c_ignbrk bool Ignore the break condition mutable c_brkint bool Signal interrupt on break condition mutable c_ignpar bool Ignore characters with parity errors mutable c_parmrk bool Mark parity errors mutable c_inpck bool Enable parity check on input mutable c_istrip bool Strip 8th bit on input characters 402 mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable c_inlcr bool Map NL to CR on in
5. Comment for type weather2 type weather2 Rain of int The comment for construtor Rain Sun The comment for constructor Sun I can continue the comment for type weather2 here because there is already a comment associated to the last constructor The comment for type my_record Chapter 15 The documentation generator ocamldoc 203 type my_record val foo int Comment for field foo val bar string Comment for field bar Continuation of comment for type my_record Comment for foo val foo string This comment is associated to foo and not to bar val bar string This comment is assciated to bar The comment for class my_class class my_class object A comment to describe inheritance from cl inherit cl The comment for attribute tutu val mutable tutu string The comment for attribute toto val toto int This comment is not attached to titi since there is a blank line before titi but is kept as a comment in the class val titi string Comment for method toto method toto string Comment for method m method m float gt int end The comment for the class type my_class_type class type my_class_type object The comment for variable x val mutable x int The commend for method m method m int gt int 204 end The comment for module Foo
6. List map f On Off int list 1 0 gt Off On list means that to match this list you should at least be able to match Off and On without argument lt On Off Number of int means that f may be applied to Off On both without argument or Number n where n is an integer The gt and lt inside the variant type shows that they may still be refined either by defining more tags or allowing less As such they contain an implicit type variable Both variant types appearing only once in the type the implicit type variables they constrain are not shown The above variant types were polymorphic allowing further refinement When writing type annotations one will most often describe fixed variant types that is types that can be no longer refined This is also the case for type abbreviations Such types do not contain lt or gt but just an enumeration of the tags and their associated types just like in a normal datatype definition type a vlist Nil Cons of a a vlist type a vlist Cons of a a vlist Nil let rec map f a vlist gt b vlist function Nil gt Nil Cons a 1 gt Cons f a map f 1 35 val map a gt b gt a vlist gt b vlist lt fun gt 70 Advanced use Type checking polymorphic variants is a subtle thing and some expressions may result in more complex type informat
7. Never use the strip command on executables produced by ocamlc custom This would remove the bytecode part of the executable dllib llibname Arrange for the C shared library dlllibname so dlllibname d1l under Windows to be loaded dynamically by the run time system ocamlrun at program start up time dllpath dir Adds the directory dir to the run time search path for shared C libraries At link time shared libraries are searched in the standard search path the one corresponding to the I option The dllpath option simply stores dir in the produced executable file where ocamlrun can find it and exploit it as described in section 10 3 dtypes Dump detailed type information The information for file z ml is put into file x annot In case of a type error dump all the information inferred by the type checker before the error The z annot file can be used with the emacs commands given in emacs caml types el to display types interactively g Add debugging information while compiling and linking This option is required in order to be able to debug the program with ocamldebug see chapter 16 i Cause the compiler to print all defined names with their inferred types or their definitions when compiling an implementation m1 file No compiled files cmo and cmi files are produced This can be useful to check the types inferred by the compiler Also since the 146 output follows the syntax of interfaces it can help in writing
8. b s 256k v 0x015 tells a subsequent ocamlrun to print backtraces for uncaught exceptions set its initial minor heap size to 1 megabyte and print a message at the start of each major GC cycle when the heap size changes and when compaction is triggered CAMLRUNPARAM If OCAMLRUNPARAM is not found in the environment then CAMLRUNPARAM will be used instead If CAMLRUNPARAM is not found then the default values will be used PATH List of directories searched to find the bytecode executable file 10 3 Dynamic loading of shared libraries On platforms that support dynamic loading ocamlrun can link dynamically with C shared libraries DLLs providing additional C primitives beyond those provided by the standard runtime system The names for these libraries are provided at link time as described in section 18 1 4 and recorded 164 in the bytecode executable file ocamlrun then locates these libraries and resolves references to their primitives when the bytecode executable program starts The ocamlrun command searches shared libraries in the following directories in the order indicated 1 Directories specified on the ocamlrun command line with the I option 2 Directories specified in the CAML_LD_LIBRARY_PATH environment variable 3 Directories specified at link time via the dllpath option to ocamlc These directories are recorded in the bytecode executable file 4 Directories specified in the file 1d conf This file res
9. module Foo struct The comment for x val x int A special comment that is kept but not associated to any element end The comment for module type my_module_type module type my_module_type sig The comment for value x val x int The comment for module M module M struct The comment for value y val y int end end Comments in m1 files A special comment is associated to an element if it is placed before the element and there is no blank line between the comment and the element Meanwhile there can be a simple comment between the special comment and the element There are two exceptions for type constructors and record fields in type definitions whose associated comment must be placed after the constructor or field definition without blank line between them The following example of file toto ml shows where to place comments in a m1 file The first special comment of the file is the comment associated to the whole module The comment for function f let fxy xty This comment is not attached to any element since there is another special comment just before the next element Chapter 15 The documentation generator ocamldoc 205 Comment for exception My_exception even with a simple comment between the special comment and the exception A simple comment exception My_exception of int gt int int Comment fo
10. val synchronize unit gt unit Synchronize the backing store and the on screen window by copying the contents of the backing store onto the graphics window val display_mode bool gt unit Set display mode on or off When turned on drawings are done in the graphics window when turned off drawings do not affect the graphics window This occurs independently of drawing into the backing store see the function Graphics remember_mode below Default display mode is on val remember_mode bool gt unit Set remember mode on or off When turned on drawings are done in the backing store when turned off the backing store is unaffected by drawings This occurs independently of drawing onto the graphics window see the function Graphics display_mode above Default remember mode is on 438 Chapter 26 The dbm library access to NDBM databases The dbm library provides access to NDBM databases under Unix NDBM databases maintain key data associations where both the key and the data are arbitrary strings They support fairly large databases several gigabytes and can retrieve a keyed item in one or two file system accesses Refer to the Unix manual pages for more information Unix Programs that use the dbm library must be linked as follows ocamlc other options dbm cma other files ocamlopt other options dbm cmxa other files For interactive use of the dbm library do ocamlmktop o mytop dbm cma mytop or if dyna
11. 328 val from_channel Pervasives in_channel gt lexbuf Create a lexer buffer on the given input channel Lexing from_channel inchan returns a lexer buffer which reads from the input channel inchan at the current reading position val from_string string gt lexbuf Create a lexer buffer which reads from the given string Reading starts from the first character in the string An end of input condition is generated when the end of the string is reached val from_function string gt int gt int gt lexbuf Create a lexer buffer with the given function as its reading method When the scanner needs more characters it will call the given function giving it a character string s and a character count n The function should put n characters or less in s starting at character number 0 and return the number of characters provided A return value of 0 means end of input Functions for lexer semantic actions The following functions can be called from the semantic actions of lexer definitions the ML code enclosed in braces that computes the value returned by lexing functions They give access to the character string matched by the regular expression associated with the semantic action These functions must be applied to the argument lexbuf which in the code generated by ocam1lex is bound to the lexer buffer passed to the parsing function val lexeme lexbuf gt string Lexing lexeme lexbuf returns the string matched by t
12. Ignore Inside Outside val place anchor anchor gt bordermode borderMode gt height int gt inside a Widget widget gt relheight float gt relwidth float gt relx float gt rely float gt width int gt x int gt y int gt b Widget widget gt unit Pack a widget inside its parent at absolute coordinates val raise_window above a Widget widget gt b Widget widget gt unit val lower_window below a Widget widget gt b Widget widget gt unit Raise or lower the window associated to a widget Event handling type modifier Alt Buttont Button2 Button3 Button4 Button5 Control Double Lock Meta Mod1 Mod2 Mod3 Mod4 Mod5 Shift Triple e event ButtonPress ButtonPressDetail of int ty ButtonRelease ButtonReleaseDetail of int Circulate ColorMap Configure Destroy Enter u Chapter 28 The LabITk library Tcl Tk GUI interface Expose FocusIn FocusOut Gravity KeyPress KeyPressDetail of string KeyRelease KeyReleaseDetail of string Leave Map Modified of modifier list event Motion Property Reparent Unmap Visibility An event can be either a basic X event or modified by a key or mouse modifier type eventInfo mutable ev_Ab
13. New variant type or record type no equation a representation The type name must be implemented by a variant type or record type with exactly the constructors or fields specified All users of the structure have access to the constructors or fields and can use them to create or inspect values of that type However users of the structure consider that type as incompatible with any other type a fresh type has been generated Re exported variant type or record type an equation a representation This case combines the previous two the representation of the type is made visible to all users and no fresh type is generated Exception specification The specification exception constr decl in a signature requires the matching structure to provide an exception with the name and arguments specified in the definition and makes the exception available to all users of the structure 128 Class specifications A specification of one or several classes in a signature is written class class spec and class spec and consists of a sequence of mutually recursive definitions of class names Class specifications are described more precisely in section 6 9 4 Class type specifications A specification of one or several classe types in a signature is written class type classtype def and classtype def and consists of a sequence of mutually recursive definitions of class type names Class type specifications are described more precisely in section 6
14. Programs that use the dynlink library simply need to link dynlink cma with their object files and other libraries Dynamic linking is available only to bytecode programs compiled with ocam1c not to native code programs compiled with ocamlopt 27 1 Module Dynlink Dynamic loading of bytecode object files Initialization val init unit gt unit Initialize the Dynlink library Must be called before any other function in this module Dynamic loading of compiled bytecode files val loadfile string gt unit Load the given bytecode object file cmo file or bytecode library file cma file and link it with the running program All toplevel expressions in the loaded compilation units are evaluated No facilities are provided to access value names defined by the unit Therefore the unit must register itself its entry points with the main program e g by modifying tables of functions val loadfile_private string gt unit Same as loadfile except that the compilation units just loaded are hidden cannot be referenced from other modules dynamically loaded afterwards 443 444 Access control val allow_only string list gt unit allow_only units restricts the compilation units that dynamically linked units can reference it only allows references to the units named in list units References to any other compilation unit will cause a Unavailable_unit error during loadfile or loadfile_private Initially just after ca
15. The inheritance construct inherit class expr allows to reuse methods and instance variables from other classes The class expression class expr must evaluate to a class body The instance variables methods and initializers from this class body are added into the current class The addition of a method will override any previously defined methods of the same name An ancestor can be bound by prepending the construct as value name to the inheritance con struct above value name is not a true variable and can only be used to select a method i e in an expression value name method name This gives access to the method method name as it was defined in the parent class even if it is redefined in the current class The scope of an ancestor binding is limited to the current class The ancestor method may be called from a subclass but only indirectly Instance variable definition The definition val mutable inst var name expr adds an instance variable inst var name whose initial value is the value of expression expr Several variables of the same name can be defined in the same class The flag mutable allows physical modification of this variable by methods An instance variables can only be used in the following methods and initializers of the class Method definition Method definition is written method method name expr The definition of a method overrides any previous definition of this method The method will be public that is not private
16. a gt gt int lt fun gt Another use of polymorphic methods is to allow some form of implicit subtyping in method arguments We have already seen in section how some functions may be polymorphic in the class of their argument This can be extended to methods class type pointO object method get_x int end class type pointO object method get_x int end class distance_point x object inherit point x method distance a pointO as a gt int fun other gt abs other get_x x end class distance_point int gt object val mutable x int method distance pointO gt int method get_offset int method get_x int method move int gt unit end let p new distance_point 3 in p distance new point 8 p distance new colored_point 1 blue int int 5 2 Note here the special syntax pointO as a we have to use to quantify the extensible part of pointO As for the variable binder it can be omitted in class specifications If you want polymorphism inside object field it must be quantified independently class multi_poly object method mi a lt ni b b gt b gt as a gt _ fun o gt o n1 true o n1 hello method m2 a b lt n2 b gt bool gt as a gt b gt _ fun o x gt o n2 x end class multi_poly object method mi lt ni a a gt a gt gt
17. a gt unit Array set a n x modifies array a in place replacing element number n with x You can also write a n lt x instead of Array set a n x Raise Invalid_argument index out of bounds if n is outside the range 0 to Array length a 1 val make int gt a gt a array Array make n x returns a fresh array of length n initialized with x All the elements of this new array are initially physically equal to x in the sense of the predicate Consequently if x is mutable it is shared among all elements of the array and modifying x through one of the array entries will modify all other entries at the same time Raise Invalid_argument ifn lt Oorn gt Sys max_array_length If the value of x isa floating point number then the maximum size is only Sys max_array_length 2 val create int gt a gt a array Deprecated Array create is an alias for Array make 20 2 val init int gt int gt a gt a array Array init n f returns a fresh array of length n with element number i initialized to the result of f i In other terms Array init n f tabulates the results of f applied to the integers O to n 1 Raise Invalid_argument ifn lt O orn gt Sys max_array_length If the return type of f is float then the maximum size is only Sys max_array_length 2 val make_matrix int gt int gt a gt a array array Array make_matrix dimx dimy e returns a two dimensional array an
18. a queue val extract a queue gt int a a queue exception Queue_is_empty end Restricting the PrioQueue structure by this signature results in another view of the PrioQueue structure where the remove_top function is not accessible and the actual representation of priority queues is hidden module AbstractPrioQueue PrioQueue PRIOQUEUE module AbstractPrioQueue PRIOQUEUE AbstractPrioQueue remove_top Unbound value AbstractPrioQueue remove_top AbstractPrioQueue insert AbstractPrioQueue empty 1 hello string AbstractPrioQueue queue lt abstr gt The restriction can also be performed during the definition of the structure as in module PrioQueue struct end PRIQQUEUE An alternate syntax is provided for the above module PrioQueue PRIQQUEUE struct end 2 3 Functors Functors are functions from structures to structures They are used to express parameterized structures a structure A parameterized by a structure B is simply a functor F with a formal parameter B along with the expected signature for B which returns the actual structure A itself The functor F can then be applied to one or several implementations B1 Bn of B yielding the corresponding structures A Any For instance here is a structure implementing sets as sorted lists parameterized by a structure providing the type of the set elements and an ordering function over this type used to keep the
19. b Bigarray fortran_layout t Extract a sub array of the given big array by restricting the last right most dimension Genarray sub_right a ofs len returns a big array with the same number of dimensions as a and the same dimensions as a except the last dimension which corresponds to the interval ofs ofs len 1 of the last dimension of a No copying of elements is involved the sub array and the original array share the same storage space In other terms the element at coordinates li1 iN of the sub array is identical to the element at coordinates i1 iN ofs of the original array a Genarray sub_right applies only to big arrays in Fortran layout Raise Invalid_arg if ofs and len do not designate a valid sub array of a that is if ofs lt 1 or len lt 0 or ofs len gt Genarray nth_dim a Genarray num_dims a 1 val slice_left Ca b Bigarray c_layout t gt int array gt a b Bigarray c_layout t Extract a sub array of lower dimension from the given big array by fixing one or several of the first left most coordinates Genarray slice_left a i1 iM returns the slice of a obtained by setting the first M coordinates to i1 iM If a has N dimensions the slice has dimension N M and the element at coordinates 462 val lj1 j N M in the slice is identical to the element at coordinates i1 iM ji j N M in the original array a No copy
20. b an extra parameter of class stack class a b stack2 object inherit a stack method fold f x b List fold_left f x 1 end class a b stack2 object val mutable 1 a list method clear unit method fold b gt a gt b gt b gt b method length int method pop a method push a gt unit end However the method fold of a given object can only be applied to functions that all have the same type let s new stack2 val s _a _b stack2 lt obj gt s fold 0 int 0 s int int stack2 lt obj gt A better solution is to use polymorphic methods which were introduced in Objective Caml version 3 05 Polymorphic methods makes it possible to treat the type variable b in the type of fold as universally quantified giving fold the polymorphic type Forall b b gt a gt b gt b gt b An explicit type declaration on the method fold is required since the type checker cannot infer the polymorphic type by itself Chapter 5 Advanced examples with classes and modules 83 class a stack3 object inherit a stack method fold b b gt a gt b gt b gt b fun f x gt List fold_left f x l end class a stack3 object val mutable 1 a list method clear unit method fold b gt a gt b gt b gt b meth
21. else see if end 107 09 T9 M2 75 exception 119 126 127 13 external 126 130 131 l 30 131 false for fun 107 108 110 21 function 109 functor 130 132 if 107 OS TT in see let i2 include 132 inherit initializer lazy Let 107 103 LTT 20 50 37 IT match method nodule 126 023 E30 E3 37 S mutable new 107 E5 object 07 1G 19 21 of see type exception open T2 T23 30 E32 or 107 008 112 private T9 21 23 24 137 E 489 rec see let sig 126 struct 130 then see if to see for true 97 try 107 108 13 sype 17 2S II val 9 2 23 7 virtual 9 27 4 25 when 07 T0 while 12 with see match try E25 29
22. label name pattern typexpr expr The table below shows the relative precedences and associativity of operators and non closed constructions The constructions with higher precedence come first For infix and prefix symbols we write to mean any symbol starting with Construction or operator Associativity prefix symbol E of L function application constructor application assert lazy left prefix E right k feza mod left Shas left ae right Gis igs right comparisons lt _ etc all other infix symbols left amp amp amp left or l left lt right if S right let match fun function try S 6 7 1 Basic expressions Constants Expressions consisting in a constant evaluate to this constant Chapter 6 The Objective Caml language 109 Value paths Expressions consisting in an access path evaluate to the value bound to this path in the current eval uation environment The path can be either a value name or an access path to a value component of a module Parenthesized expressions The expressions expr and begin expr end have the same value as expr Both constructs are semantically equivalent but it is good style to use begin end inside control structures if then begin end else begin end and for the other grouping situations Parenthesized expressions can contain a type constraint as in expr
23. module NoCaseString struct type t string let compare si s2 OrderedString compare String lowercase s1 String lowercase s2 end module NoCaseString sig type t string val compare string gt string gt comparison end module NoCaseStringSet AbstractSet NoCaseString module NoCaseStringSet sig type element NoCaseString t type set AbstractSet NoCaseString set val empty set val add element gt set gt set val member element gt set gt bool end NoCaseStringSet add FOO AbstractStringSet empty This expression has type AbstractStringSet set AbstractSet OrderedString set but is here used with type NoCaseStringSet set AbstractSet NoCaseString set Notice that the two types AbstractStringSet set and NoCaseStringSet set are not compatible and values of these two types do not match This is the correct behavior even though both set types contain elements of the same type strings both are built upon different orderings of that type and different invariants need to be maintained by the operations being strictly increasing for the standard ordering and for the case insensitive ordering Applying operations from AbstractStringSet to values of type NoCaseStringSet set could give incorrect results or build lists that violate the invariants of NoCaseStringSet 2 5 Modules and separate compilation All examples of modules so far have been given in the conte
24. object self val mutable x x_init method virtual get_x int method get_offset self get_x x_init method virtual move int gt unit end class virtual abstract_point int gt Chapter 3 Objects in Caml object val mutable x int method get_offset int method virtual get_x int method virtual move int gt unit end class point x_init object inherit abstract_point x_init method get_x x method move d x lt x d end class point int gt object val mutable x int method get_offset int method get_x int method move int gt unit end 3 6 Private methods 39 Private methods are methods that do not appear in object interfaces They can only be invoked from other methods of the same object class restricted_point x_init object self val mutable x x_init method get_x x method private move d x lt x d method bump self move 1 end class restricted_point int gt object val mutable x int method bump unit method get_x int method private move int gt unit end let p new restricted_point 0 val p restricted_point lt obj gt p move 10 This expression has type restricted_point It has no method move 40 p bump unit Private methods are inherited they are by default visible in subclasses unless they are hidden by signature matching as described below Private methods ca
25. typexpr label name typexpr gt typexpr typexpr typexpr T typeconstr typexpr typeconstr typexpr typexpr typeconstr typexpr as ident variant type lt gt lt method type method type gt class path typexpr class path typexpr typexpr class path poly typexpr typexpr ident typexpr method type method name poly typexpr The table below shows the relative precedences and associativity of operators and non closed type constructions The constructions with higher precedences come first Operator Associativity Type constructor application gt right as Type expressions denote types in definitions of data types as well as in type constraints over patterns and expressions Type variables The type expression ident stands for the type variable named ident The type expression _ stands for an anonymous type variable In data type definitions type variables are names for the data 100 type parameters In type constraints they represent unspecified types that can be instantiated by any type to satisfy the type constraint In general the scope of a named type variable is the whole enclosing definition they can only be generalized when leaving this scope Anonymous variables have no such restriction Parenthesized types The type expression typexpr denotes the same type as typexpr Function types The type e
26. Array operations 2 0 0 0 ee ee 20 3 Module Buffer Extensible string buffers 0 0 2 02005 20 4 Module Callback Registering Caml values with the C runtime 20 5 20 6 Module Char Character operations 2 oa a a Module Complex Complex numbers 2 0 a 20 7 Module Digest MD5 message digest 2 0 ee 20 8 Module Filename Operations on filenames 2 02004 20 9 Module Format Pretty printing 2 0 0 02 0000 eee eee 20 10 Module Gc Memory management control and statistics finalised values Seiad Chee eRe eRe arg ad Su A tee wots ek eee ied SG ee bapa e s ee ei ee be GOH bw ied a as ae ee es Sik Lee a as ae oe Gate peo hdewes i eee Sgr Ee TANIORA E E EE ee eee 20 22 Module Parsing The run time library for parsers generated by ocamlyacc 20 23 Module Printexc Facilities for printing exceptions 20 24 Module Printf Formatted output functions oaoa a 20 25 Module Queue First in first out queues o oo a e a ee 20 26 Module Random Pseudo random number generators PRNG 20 27 Module Scanf Formatted input functions ooa 20 28 Module Set Sets over ordered types 2 aa a a ee 20 29 Module Sort Sorting and merging lists oo a aa 022220004 20 30 Module Stack Last in first out stacks ooa a aaa 02 02 0000 000004 20 31 Module StdLabels Standard labeled l
27. Glass Interfaces mos nocd acp Bk e e e a E e eee ee ee ee e a ee e Weg 41 3 8 Inheritance s 4 a 8k ae a a E E a a E ee OR eee h ew E A 42 3 9 Multiple inheritance 2 ee ee 43 3 10 Parameterized classes 2 oa a a a a 44 aT leg ok ay gis a AR N ote wk Mer gp dees ate ghey a EA og 47 ge ices yp Geen Pare a a ee Meee eee Cpe ae Sewn ee eet He ees See ee a 50 Ge Sees ee eee Syne Se ee aoe ee aes Se Me nee eee Ge ee oem Ge ch nee eee Se 53 Pete Ben acy Be a Ark ee eos 2 a amp ets ea a eae Be d 54 3 15 Recursive classes ooo a a a 57 A 3 16 Binary methods 0 000 cee ee 3 17 Friends Labels and variants 4 1 Labels 4 2 Polymorphic variants 2 2 ee 5 Advanced examples with classes and modules 5 1 Extended example bank accounts 2 00 0 0 02 ee ee ee ees 5 2 Simple modules as classes o oo oa a eea a ke a de E 6 1 Lexical conventions a o oa aoa a a 62 Valy s s irse s as popom ee me ee ee Ss a a OR EG A ee ee A C3 NAMES eeen e ee a aw aa oe a a a BO LA ee OP A oo A we 6 4 Type expressions 2 a 6 5 Constants soci ee Rae ate Sow wo Re eee el Ree Soe Fk ee eS 6 6 Patternsh esre e cee a a eee ee HO ae A ee Be pele 6 7 Expressions 2 0 a 6 8 Type and exception definitions o a a e a 0 0002 eee ee ee ee 6 9 Classes 6 10 Module types module specifications 6 11 Module expressions module implementations Dhaest gee e
28. The expression include module expr in a structure re exports in the current structure all defi nitions of the structure denoted by module expr For instance if the identifier S is bound to the module struct type t int let x 2 end the module expression struct include S let y x 1 t end is equivalent to the module expression struct type t int let x 2 let y x 1 t end The difference between open and include is that open simply provides short names for the com ponents of the opened structure without defining any components of the current structure while include also adds definitions for the components of the included structure 6 11 3 Functors Functor definition The expression functor module name module type gt module expr evaluates to a functor that takes as argument modules of the type module type binds module name to these modules evaluates module expr in the extended environment and returns the resulting modules as results No restrictions are placed on the type of the functor argument in particular a functor may take another functor as argument higher order functor Functor application The expression module expr module expr evaluates module expr to a functor and module expr to a module and applies the former to the latter The type of module expry must match the type expected for the arguments of the functor module expry Chapter 6 The Objective Caml language 133 6 12 Compilatio
29. Zs i x 1 or even shorter printf x i 1 Rule of thumb for casual users of this library e use simple boxes as obtained by open_box 0 e use simple break hints as obtained by print_cut that outputs a simple break hint or by print_space that outputs a space indicating a break hint e once a box is opened display its material with basic printing functions e g print_int and print_string e when the material for a box has been printed call close_box to close the box e at the end of your routine evaluate print_newline to close all remaining boxes and flush the pretty printer The behaviour of pretty printing commands is unspecified if there is no opened pretty printing box Each box opened via one of the open_ functions below must be closed using close_box for proper formatting Otherwise some of the material printed in the boxes may not be output or may be formatted incorrectly In case of interactive use the system closes all opened boxes and flushes all pending text as with the print_newline function after each phrase Each phrase is therefore executed in the initial state of the pretty printer Boxes val open_box int gt unit open_box d opens a new pretty printing box with offset d This box is the general purpose pretty printing box Material in this box is displayed horizontal or vertical break hints inside the box may lead to a new line if there is no more room on the lin
30. a circle c method color center color end class a colored_circle 2a gt object constraint a colored_point val mutable center a method center a method color string method move int gt unit method set_center a gt unit end Chapter 3 Objects in Caml 47 3 11 Polymorphic methods While parameterized classes may be polymorphic in their contents they are not enough to allow polymorphism of method use A classical example is defining an iterator List fold_left a gt b gt a gt a gt b list gt a lt fun gt class a intlist 1 int list object method empty 1 method fold f accu a List fold_left f accu 1 end class a intlist int list gt object method empty bool method fold a gt int gt a gt a gt a end At first look we seem to have a polymorphic iterator however this does not work in practice let 1 new intlist 1 2 3 val 1 _a intlist lt obj gt l fold fun x y gt x y 0 int 6 15 int intlist lt obj gt l fold fun s x gt s string_of_int x This expression has type int but is here used with type string Our iterator works as shows its first use for summation However since objects themselves are not polymorphic only their constructors are using the fold method fixes its type for this indivi
31. gt val mutable center a method center a method move int gt unit method set_center a gt unit 46 end An alternate definition of circle using a constraint clause in the class definition is shown below The type point used below in the constraint clause is an abbreviation produced by the definition of class point This abbreviation unifies with the type of any object belonging to a subclass of class point It actually expands to lt get_x int move int gt unit gt This leads to the following alternate definition of circle which has slightly stronger constraints on its argument as we now expect center to have a method get_x class a circle c a object constraint a point val mutable center c method center center method set_center c center lt c method move center move end class a circle 2a gt object constraint a point val mutable center a method center a method move int gt unit method set_center a gt unit end The class colored_circle is a specialized version of class circle that requires the type of the center to unify with colored_point and adds a method color Note that when specializing a parameterized class the instance of type parameter must always be explicitly given It is again written between and class a colored_circle c object constraint a colored_point inherit
32. include lt caml callback h gt int fib int n static value fib_closure NULL if fib_closure NULL fib_closure caml_named_value fib return Int_val callback fib_closure Val_int n 254 char format_result int n static value format_result_closure NULL if format_result_closure NULL format_result_closure caml_named_value format_result return strdup String_val callback format_result_closure Val_int n We copy the C string returned by String_val to the C heap so that it remains valid after garbage collection We now compile the Caml code to a C object file and put it in a C library along with the stub code in modwrap c and the Caml runtime system ocamlc custom output obj o modcaml o mod ml ocamlc c modwrap c cp usr local lib ocaml libcamlrun a mod a ar r mod a modcaml o modwrap o One can also use ocamlopt output obj instead of ocamlc custom output obj In this case replace libcamlrun a the bytecode runtime library by libasmrun a the native code runtime library Now we can use the two fonctions fib and format_result in any C program just like regular C functions Just remember to call caml_startup once before File main c a sample client for the Caml functions include lt stdio h gt int main int argc char argv int result Initialize Caml code caml_startup argv Do some computation result fib 10 printf fib
33. lognot int64 gt int64 Bitwise logical negation shift_left int64 gt int gt int64 Int64 shift_left x y shifts x to the left by y bits The result is unspecified if y lt O or y gt 64 shift_right int64 gt int gt int64 Int64 shift_right x y shifts x to the right by y bits This is an arithmetic shift the sign bit of x is replicated and inserted in the vacated bits The result is unspecified if y lt 0 or y gt 64 shift_right_logical int64 gt int gt int64 Int64 shift_right_logical x y shifts x to the right by y bits This is a logical shift zeroes are inserted in the vacated bits regardless of the sign of x The result is unspecified if y lt Oory gt 64 of_int int gt int64 Convert the given integer type int to a 64 bit integer type int64 to_int int64 gt int Convert the given 64 bit integer type int64 to an integer type int On 64 bit platforms the 64 bit integer is taken modulo 263 i e the high order bit is lost during the conversion On 32 bit platforms the 64 bit integer is taken modulo 2 i e the top 33 bits are lost during the conversion Chapter 20 The standard library 325 val of_float float gt int64 Convert the given floating point number to a 64 bit integer discarding the fractional part truncate towards 0 The result of the conversion is undefined if after truncation the number is outside the range Int64 min_int 20 14 Int64 max_int 20 14
34. power_big_int_positive_big_int 412 power_big_int_positive_int power_int_positive_big_int power_int_positive_int power_num pp_close_box 308 pp_close_tag pp_close_tbox 308 pp_force_newline 308 pp_get_all_formatter_output_functions 309 pp_get_ellipsis_text 809 pp_get_formatter_output_functions 309 pp_get_formatter_tag_functions 309 pp_get_margin 308 pp_get_mark_tags 808 pp_get_max_boxes 809 pp_get_max_indent 308 pp_get_print_tags 308 pp_open_box 308 pp_open_hbox 308 pp_open_hovbox 308 pp_open_hvbox 308 pp_open_tag pp_open_tbox 308 pp_open_vbox 808 pp_over_max_boxes 309 pp_print_as 808 pp_print_bool pp_print_break 308 pp_print_char 308 pp_print_cut 808 pp_print_float 308 pp_print_flush 308 pp_print_if_newline 308 pp_print_int 308 pp_print_newline 308 pp_print_space pp_print_string 308 pp_print_tab pp_print_tbreak pp_set_all_formatter_output_functions 309 484 pp_set_ellipsis_text 809 pp_set_formatter_out_channel pp_set_formatter_output_functions 309 pp_set_formatter_tag_functions 309 pp_set_margin 308 pp_set_mark_tags 808 pp_set_max_boxes 308 pp_set_max_indent pp_set_print_tags 308 pp_set_tab pp_set_tags 308 pred 270 21 B23 B33 pred_big_int pred_num 409 prerr_char prerr_endline prerr_float prerr_int prerr_newline prerr_string print 342
35. val substring string gt int gt int gt t Digest substring s ofs len returns the digest of the substring of s starting at character number ofs and containing len characters val channel Pervasives in_channel gt int gt t If len is nonnegative Digest channel ic len reads len characters from channel ic and returns their digest or raises End_of_file if end of file is reached before len characters are read If len is negative Digest channel ic len reads all characters from ic until end of file is reached and return their digest val file string gt t Return the digest of the file whose name is given val output Pervasives out_channel gt t gt unit Write a digest on the given output channel 298 val val input Pervasives in_channel gt t Read a digest from the given input channel to_hex t gt string Return the printable hexadecimal representation of the given digest 20 8 Module Filename Operations on file names val val val val val val val val val current_dir_name string The conventional name for the current directory e g in Unix parent_dir_name string The conventional name for the parent of the current directory e g in Unix concat string gt string gt string concat dir file returns a file name that designates file file in directory dir is_relative string gt bool Return true if the file name is relative to the c
36. 73 74 val mutable balance Euro c method balance Euro c method deposit Euro c gt unit method withdraw Euro c gt Euro c end let c new account in c deposit euro 100 c withdraw euro 50 Euro c lt obj gt We now refine this definition with a method to compute interest class account_with_interests object self inherit account method private interest self deposit self balance times 0 03 end class account_with_interests object val mutable balance Euro c method balance Euro c method deposit Euro c gt unit method private interest unit method withdraw Euro c gt Euro c end We make the method interest private since clearly it should not be called freely from the outside Here it is only made accessible to subclasses that will manage monthly or yearly updates of the account We should soon fix a bug in the current definition the deposit method can be used for with drawing money by depositing negative amounts We can fix this directly class safe_account object inherit account method deposit x if zero leq x then balance lt balance plus x end class safe_account object val mutable balance Euro c method balance Euro c method deposit Euro c gt unit method withdraw Euro c gt Euro c end However the bug might be fixed more safely by the following definition class safe_account object inherit ac
37. A registered global variable v can be un registered by calling remove_global_root amp v Note The CAML macros use identifiers local variables type identifiers structure tags that start with caml1__ Do not use any identifier starting with caml__ in your programs 18 5 2 Low level interface We now give the GC rules corresponding to the low level allocation functions alloc_small and alloc_shr You can ignore those rules if you stick to the simplified allocation function alloc Rule 5 After a structured block a block with tag less than No_scan_tag is allocated with the low level functions all fields of this block must be filled with well formed values before the next allocation operation If the block has been allocated with alloc_smal1 filling is performed by direct assignment to the fields of the block Field v n wn If the block has been allocated with alloc_shr filling is performed through the initialize function initialize kField v n un 246 The next allocation can trigger a garbage collection The garbage collector assumes that all structured blocks contain well formed values Newly created blocks contain random data which generally do not represent well formed values If you really need to allocate before the fields can receive their final value first initialize with a constant value e g Val_unit then allocate then modify the fields with the correct value see rule 6 Rule 6 Direct assignment to a field
38. File descriptor for standard input val stdout file_descr File descriptor for standard output val stderr file_descr File descriptor for standard error type open_flag O_RDONLY Open for reading O_WRONLY Open for writing O_RDWR Open for reading and writing O_NONBLOCK Open in non blocking mode O_APPEND Open for append O_CREAT Create if nonexistent O_TRUNC Truncate to 0 length if existing O_EXCL Fail if existing O_NOCTTY Don t make this dev a controlling tty O_DSYNC Writes complete as Synchronised I O data integrity completion O_SYNC Writes complete as Synchronised I O file integrity completion O_RSYNC Chapter 21 The unix library Unix system calls 379 Reads complete as writes depending on O_SYNC O_DSYNC The flags to Unix openfile 21 1 type file_perm int The type of file access rights e g 00640 is read and write for user read for group none for others val openfile string gt open_flag list gt file_perm gt file_descr Open the named file with the given flags Third argument is the permissions to give to the file if it is created Return a file descriptor on the named file val close file_descr gt unit Close a file descriptor val read file_descr gt string gt int gt int gt int read fd buff ofs len reads len characters from descriptor fd storing them in string buff starting at position ofs in string buff Return the number of ch
39. OK to coerce directly from WINDOW to value since that s a block created by malloc value curses_wrefresh value win 1 CAMLparam1 win wrefresh WINDOW win CAMLreturn Val_unit J value curses_newwin value nlines value ncols value x0 value y0 CAMLparam4 nlines ncols x0 y0 CAMLreturn value newwin Int_val nlines Int_val ncols Int_val x0 Int_val y0 value curses_addch value c CAMLparam1 c addch Int_val c Characters are encoded like integers CAMLreturn Val_unit value curses_addstr value s Chapter 18 Interfacing C with Objective Caml 249 CAMLparam1 s addstr String_val s CAMLreturn Val_unit This goes on for pages The file curses c can be compiled with cc c I usr local lib ocaml curses c or even simpler ocamlc c curses c When passed a c file the ocamlc command simply calls the C compiler on that file with the right I option Now here is a sample Caml program test ml that uses the curses module open Curses let main_window initscr in let small_window newwin 10 5 20 10 in mvwaddstr main_window 10 2 Hello mvwaddstr small_window 4 3 world refresh for i 1 to 100000 do done endwin To compile this program run ocamlc c test ml Finally to link everything together ocamlc custom o test test cmo curses o cclib lcurses On some machines you may need to put cclib ltermcap or cclib lcur
40. Odoc_args set_doc_generator Odoc_args doc_generator gt unit which installs the new documentation generator The following example shows how to define and install a new documentation generator See the odoc_fhtml generator in the Ocamldoc Hump for a complete example class my_doc_gen object k method generate module_list CF 0 k end let my_generator new my_doc_gen let _ Odoc_args set_doc_generator my_generator gt Odoc_args doc_generator Note The new class can inherit from Odoc_html html Odoc_latex latex Odoc_man man Odoc_texi texi or Odoc_dot dot and redefine only some methods to benefit from the existing methods 15 3 2 Handling custom tags Making a custom generator handle custom tags see 15 2 5 is very simple For HTML Here is how to develop a HTML generator handling your custom tags The class Odoc_html html inherits from the class Odoc_html info containing a field tag_functions which is a list pairs composed of a custom tag e g foo and a function taking a text and returning HTML code of type string To handle a new tag bar create a HTML generator class from the existing one and complete the tag_functions field class my_gen object self inherit Odoc_html html Return HTML code for the given text of a bar tag 212 method html_of_bar t your code here initializer tag_functions lt bar self html_of_bar tag_functions end Anothe
41. a Array1 get a x or alternatively a x returns the element of a at index x x must be greater or equal than 0 and strictly less than Array1 dim a if a has C layout Ifa has Fortran layout x must be greater or equal than 1 and less or equal than Array1 dim a Otherwise Invalid_arg is raised 464 val set Ca b c t gt int gt a gt unit Arrayl set a x v also written a x lt v stores the value v at index x in a x must be inside the bounds of a as described in Bigarray Array1 get 29 1 otherwise Invalid_arg is raised val sub a b c t gt int gt int gt a b c t Extract a sub array of the given one dimensional big array See Genarray sub_left for more details val blit a b c t gt a b c t gt unit Copy the first big array to the second big array See Genarray blit for more details val fill Ca b c t gt a gt unit Fill the given big array with the given value See Genarray fill for more details val of_array Ca b Bigarray kind gt c Bigarray layout gt a array gt a b c t Build a one dimensional big array initialized from the given array val map_file Unix file_descr gt Ca b Bigarray kind gt c Bigarray layout gt bool gt int gt a b c t Memory mapping of a file as a one dimensional big array See Bigarray Genarray map_file for more details end One dimension
42. a program must be compiled entirely with ocamlopt or entirely with ocamlc Native code object files produced by ocamlopt cannot be loaded in the toplevel system ocaml 11 1 Overview of the compiler The ocamlopt command has a command line interface very close to that of ocamlc It accepts the same types of arguments and processes them sequentially e Arguments ending in mli are taken to be source files for compilation unit interfaces In terfaces specify the names exported by compilation units they declare value names with their types define public data types declare abstract data types and so on From the file x mli the ocamlopt compiler produces a compiled interface in the file z cmi The interface produced is identical to that produced by the bytecode compiler ocamlc e Arguments ending in ml are taken to be source files for compilation unit implementations Implementations provide definitions for the names exported by the unit and also contain expressions to be evaluated for their side effects From the file x m1 the ocamlopt compiler produces two files z o containing native object code and z cmx containing extra informa tion for linking and optimization of the clients of the unit The compiled implementation should always be referred to under the name z cmx when given a o file ocamlopt assumes that it contains code compiled from C not from Caml The implementation is checked against the interface file x mli if it exists
43. always raise Not_found the domain PF_UNIX is not supported PF_INET is fully supported does not work under Windows 95 98 ME works fine under NT 2000 XP not implemented use threads not implemented Chapter 22 The num library arbitrary precision rational arithmetic The num library implements integer arithmetic and rational arithmetic in arbitrary precision More documentation on the functions provided in this library can be found in The CAML Numbers Reference Manual by Val rie M nissier Morain technical report 141 INRIA july 1992 available electronically ftp ftp inria fr INRIA publication RT RT 0141 ps gz Programs that use the num library must be linked as follows ocamlc other options nums cma other files ocamlopt other options nums cmxa other files For interactive use of the nums library do ocamlmktop o mytop nums cma mytop or if dynamic linking of C libraries is supported on your platform start ocaml and type 1load nums cma 22 1 Module Num Operation on arbitrary precision numbers Numbers type num are arbitrary precision rational numbers plus the special elements 1 0 infin ity and 0 0 undefined type num Int of int Big_int of Big_int big_int Ratio of Ratio ratio The type of numbers 407 408 Arithmetic operations val val val val val val val val val val val val val val val num gt num gt num Same
44. exception attribute method or section modules string string insert an index table for the given module names Used in HTML only indexlist insert a table of links to the various indexes types values modules Used in HTML only 7 text set text in superscript _ text set text in subscript escaped_string typeset the given string as is special characters P and must be escaped by a blank_line force a new line list tert 1i text A shortcut syntax exists for lists and enumerated lists Here is a b list Chapter 15 The documentation generator ocamldoc 209 item 1 item 2 item 3 The list is ended by the blank line is equivalent to Here is a b list ul item 1 item 2 item 3 The list is ended by the blank line The same shortcut is available for enumerated lists using instead of Note that only one list can be defined by this shortcut in nested lists In the description of a value type exception module module type class or class type the first sentence is sometimes used in indexes or when just a part of the description is needed The first sentence is composed of the first characters of the description until e the first dot followed by a blank or e the first blank line outside of the following text formatting ul list ol list string stringl v st
45. float gt float The usual hyperbolic trigonometric functions ceil float gt float See Pervasives floor f floor float gt float Round the given float to an integer value floor f returns the greatest integer value less than or equal to f ceil f returns the least integer value greater than or equal to f abs_float float gt float Return the absolute value of the argument mod_float float gt float gt float mod_float a b returns the remainder of a with respect to b The returned value isa n b where n is the quotient a b rounded towards zero to an integer frexp float gt float int frexp f returns the pair of the significant and the exponent of f When f is zero the significant x and the exponent n of f are equal to zero When f is non zero they are defined byf x 2 nandO 5 lt x lt 1 0 ldexp float gt int gt float ldexp x n returns x 2 n modf float gt float float modf f returns the pair of the fractional and integral part of f float int gt float Same as Pervasives float_of_int 19 2 float_of_int int gt float 274 val val val val val val val val Convert an integer to floating point truncate float gt int Same as Pervasives int_of_float 19 2 int_of_float float gt int Truncate the given floating point number to an integer The result is unspecified if it falls outside the range of repre
46. gt a gt a array create int gt a gt a array init int gt f int gt a gt a array make_matrix dimx int gt dimy int gt a gt a array array create_matrix dimx int gt dimy int gt a gt a array array append a array gt a array gt a array concat a array list gt a array sub a array gt pos int gt len int gt a array copy a array gt a array fill a array gt pos int gt len int gt a gt unit blit src a array gt src_pos int gt dst a array gt dst_pos int gt len int gt unit val val val val val val val val val val val val val end to_list a array gt a list of_list a list gt a array iter f a gt unit gt a array gt unit map f a gt b gt a array gt b array iteri f int gt a gt unit gt a array gt unit mapi f int gt a gt b gt a array gt b array fold_left f a gt b gt a gt init a gt b array gt a fold_right f a gt b gt b gt a array gt init b gt b sort cmp a gt a gt int gt a array gt unit stable_sort cmp a gt a gt int gt a array gt unit fast_sort cmp a gt a gt int gt a array gt unit unsafe_get a array gt int gt a unsafe_set a array gt
47. gt int gt char gt int Same as String rindex 20 33 but start searching at the character position given as second argument String rindex s c is equivalent to String rindex_from s String length s 1 c val contains string gt char gt bool String contains s c tests if character c appears in the string s val contains_from string gt int gt char gt bool String contains_from s start c tests if character c appears in the substring of s starting from start to the end of s Raise Invalid_argument if start is not a valid index of s val rcontains_from string gt int gt char gt bool String rcontains_from s stop c tests if character c appears in the substring of s starting from the beginning of s to index stop Raise Invalid_argument if stop is not a valid index of s val uppercase string gt string Return a copy of the argument with all lowercase letters translated to uppercase including accented letters of the ISO Latin 1 8859 1 character set val lowercase string gt string Return a copy of the argument with all uppercase letters translated to lowercase including accented letters of the ISO Latin 1 8859 1 character set val capitalize string gt string Return a copy of the argument with the first character set to uppercase val uncapitalize string gt string Return a copy of the argument with the first character set to lowercase type t string An alias for the
48. gt object method bump unit method get_x int end end module Point POINT struct class restricted_point restricted_point end module Point POINT 3 8 Inheritance We illustrate inheritance by defining a class of colored points that inherits from the class of points This class has all instance variables and all methods of class point plus a new instance variable c and a new method color class colored_point x c string object inherit point x val c c method color c end class colored_point int gt string gt object val c string val mutable x int method color string method get_offset int method get_x int method move int gt unit end let p new colored_point 5 red val p colored_point lt obj gt p get_x p color int string 5 red A point and a colored point have incompatible types since a point has no method color However the function get_x below is a generic function applying method get_x to any object p that has this method and possibly some others which are represented by an ellipsis in the type Thus it applies to both points and colored points let get_succ_x p p get_x 1 val get_succ_x lt get_x int gt gt int lt fun gt Chapter 3 Objects in Caml 43 get_succ_x p get_succ_x p int 8 Methods need not be declared previously as shown by the example let set_x
49. gt string Return a string representing the given character with special characters escaped following the lexical conventions of Objective Caml val lowercase char gt char Convert the given character to its equivalent lowercase character val uppercase char gt char Convert the given character to its equivalent uppercase character type t char An alias for the type of characters val compare t gt t gt int The comparison function for characters with the same specification as Pervasives compare 19 2 Along with the type t this function compare allows the module Char to be passed as argument to the functors Set Make 20 28 and Map Make 20 18 20 6 Module Complex Complex numbers This module provides arithmetic operations on complex numbers Complex numbers are repre sented by their real and imaginary parts cartesian representation Each part is represented by a double precision floating point number type float type t re float im float 296 The type of complex numbers re is the real part and im the imaginary part val zero t The complex number 0 val one t The complex number 1 vali t The complex number i val neg t gt t Unary negation val conj t gt t Conjugate given the complex x i y returns x i y val add t gt t gt t Addition val sub t gt t gt t Subtraction val mul t gt t gt t Multiplication va
50. if any of the definition states so A private method method private method name expr is a method that can only be invoked on self from other methods of the current class as well as of subclasses of the current class This invocation is performed using the expression value name method name where value name is directly bound to self at the beginning of the class definition Private methods do not appear in 124 object types A method may have both public and private definitions but as soon as there is a public one all subsequent definitions will be made public Methods may have an explicitly polymorphic type allowing them to be used polymorphically in programs even for the same object The explicit declaration may be done in one of three ways 1 by giving an explicit polymorphic type in the method definition immediately after the method name i e method private method name gt ident typexpr expr 2 by a forward declaration of the explicit polymorphic type through a virtual method definition 3 by importing such a declaration through inheritance and or constraining the type of self Some special expressions are available in method bodies for manipulating instance variables and duplicating self expr inst var name lt expr lt inst var name expr inst var name expr gt The expression inst var name lt expr modifies in place the current object by replacing the value associated to inst var nam
51. if n is outside the range 0 to String length s 1 val create int gt string String create n returns a fresh string of length n The string initially contains arbitrary characters Raise Invalid_argument ifn lt O orn gt Sys max_string_length val make int gt char gt string String make n c returns a fresh string of length n filled with the character c Raise Invalid_argument ifn lt Oorn gt Sys max_string_length 20 34 val copy string gt string 362 val val val val val val val val val Return a copy of the given string sub string gt int gt int gt string String sub s start len returns a fresh string of length len containing the characters number start to start len 1 of string s Raise Invalid_argument if start and len do not designate a valid substring of s that is if start lt 0 or len lt 0 or start len gt String length 20 33 s fill string gt int gt int gt char gt unit String fill s start len c modifies string s in place replacing the characters number start to start len 1 by c Raise Invalid_argument if start and len do not designate a valid substring of s blit string gt int gt string gt int gt int gt unit String blit src srcoff dst dstoff len copies len characters from string src starting at character number srcoff to string dst starting at character number dstoff It works correctly even if src and dst a
52. int32 Int32 shift_right_logical x y shifts x to the right by y bits This is a logical shift zeroes are inserted in the vacated bits regardless of the sign of x The result is unspecified if y lt Oory gt 32 of_int int gt int32 Convert the given integer type int to a 32 bit integer type int32 to_int int32 gt int Convert the given 32 bit integer type int32 to an integer type int On 32 bit platforms the 32 bit integer is taken modulo 231 i e the high order bit is lost during the conversion On 64 bit platforms the conversion is exact of_float float gt int32 Convert the given floating point number to a 32 bit integer discarding the fractional part truncate towards 0 The result of the conversion is undefined if after truncation the number is outside the range Int32 min_int 20 13 Int32 max_int 20 13 to_float int32 gt float Convert the given 32 bit integer to a floating point number of_string string gt int32 Convert the given string to a 32 bit integer The string is read in decimal by default or in hexadecimal octal or binary if the string begins with Ox Oo or Ob respectively Raise Failure int_of_string if the given string is not a valid representation of an integer or if the integer represented exceeds the range of integers representable in type int32 to_string int32 gt string Return the string representation of its argument in signed decimal bits_of_floa
53. k x gt end class safe_money float gt object a val repr float method print unit method times float gt a end Here the representation of the object is known only to a particular object To make it available to other objects of the same class we are forced to make it available to the whole world However we can easily restrict the visibility of the representation using the module system module type MONEY sig type t class c float gt object a val repr t method value t method print unit method times float gt a method leq a gt bool method plus a gt a end end module Euro MONEY struct type t float class c x object self a val repr x method value repr HH HHH H FH HHH H HH HHHH Chapter 3 Objects in Caml 61 method print print_float repr method times k lt repr k x gt method leq p a repr lt p value method plus p a lt repr x p value gt end HH HH HF H end Another example of friend functions may be found in section These examples occur when a group of objects here objects of the same class and functions should see each others internal representation while their representation should be hidden from the outside The solution is always to define all friends in the same module give access to the representation and use a signature constraint to make the representation abs
54. linked to name name Cexpr CXpl Xpr 3 3 CXPly An expression e is said to be immediately linked to the variable name in the following cases e eis name e e has the form expr expr where expr is immediately linked to name e e has the form let rec xname expr and and xname expr in exprg where expro is immediately linked to name or to one of the xname such that expr is immediately linked to name Chapter 7 Language extensions 137 7 4 Range patterns In patterns Objective Caml recognizes the form c gt d two character literals separated by as shorthand for the pattern e lee leo ll lean lt d where c1 C2 Cn are the characters that occur between c and din the ASCII character set For instance the pattern 0 9 matches all characters that are digits 7 5 Assertion checking Objective Caml supports the assert construct to check debugging assertions The expression assert expr evaluates the expression expr and returns if expr evaluates to true Otherwise the exception Assert_failure is raised with the source file name and the location of expr as arguments Assertion checking can be turned off with the noassert compiler option As a special case assert false is reduced to raise Assert_failure which is poly morphic and is not turned off by the noassert option 7 6 Lazy evaluation The expression lazy expr returns a value v
55. numdims p dims Return a Caml big array wrapping the data pointed to by p kindis the kind of array elements one of the BIGARRAY_ kind constants above layout is BIGARRAY_C_LAYOUT for an array with C layout and BIGARRAY_FORTRAN_LAYOUT for an array with Fortran layout numdims is the number of dimensions in the array dims is an array of numdims long integers giving the sizes of the array in each dimension e alloc_bigarray_dims kind layout numdims p long dimi long dima long dimMnumdims Same as alloc_bigarray but the sizes of the array in each dimension are listed as extra arguments in the function call rather than being passed as an array The following example illustrates how statically allocated C and Fortran arrays can be made avail able to Caml extern long my_c_array 100 200 extern float my_fortran_array_ 300 400 value caml_get_c_array value unit long dims 2 dims 0 100 dims 1 200 return alloc_bigarray BIGARRAY_NATIVEINT BIGARRAY_C_LAYOUT 2 my_c_array dims value caml_get_fortran_array value unit return alloc_bigarray_dims BIGARRAY_FLOAT32 BIGARRAY_FORTRAN_LAYOUT 2 my_fortran_array_ 300L 400L Part V Appendix 473 INDEX TO THE LIBRARY Index to the library amp aa 1 MiNi Co Dd 2 r ll wero wy eS re Yl DI DO RO Lool Oj o wj co NN ll e SNIS ee ZN BI I a ot D gt Vv w b
56. of the break may be optionally specified with the following syntax the lt character followed by an integer nspaces value then an integer offset and a closing gt character If no parameters are provided the good break defaults to a space flush the pretty printer as with print_flush This is equivalent to the conversion flush the pretty printer and output a new line as with print_newline lt n gt print the following item as if it were of length n Hence printf lt 0 gt s arg is equivalent to print_as O arg If lt n gt is not followed by a conversion specification then the following character of the format is printed as if it were of length n open a tag The name of the tag may be optionally specified with the following syntax the lt character followed by an optional string specification and the closing gt character The string specification is any character string that does not contain the closing character gt If omitted the tag name defaults to the empty string For more details about tags see the functions open_tag and close_tag close the most recently opened tag print a plain character Example printf s d x 1 is equivalent to open_box print_string x print_space print_int 1 close_box It prints x 1 withina pretty printing box val printf a formatter unit Pervasives format gt a Same as fprintf above but output on st
57. print_as 801 print_bool 801 print_break 301 print_char 277 301 print_cut 301 print_endline print_float print_flush print_if_newline 802 print_int print_newline print_space 801 print_stat 314 print_string print_tab 303 print_tbreak Printexc Printf 342 printf process_status process_times 389 prohibit 444 protocol_entry 398 push 345 356 putenv 376 Queue quick_stat 313 quo_num quomod_big_int quote raise 268 raise_window 50 Random ratio_of_num rcontains_from read read_float read_int read_key read_line readdir readlink really_input Z281 receive recv recvfron red ref regexp regexp_case_fold regexp_string regexp_string_case_fold register register_exception ren B21 B25 E35 remember_mode 43 renove BIS B19 B34 B53 TON E09 AO remove_assoc remove_assq rename replace 440 replace_first replace_matched reset 293 reshape 70 reshape_1 70 reshape_2 70 3 70 reshape_3 INDEX TO THE LIBRARY rev B20 B57 rev_append rev_map 830 rev_map2 rewinddir 385 rgb rhs_end rhs_end_pos rhs_start 341 rhs_start_pos rindex rindex_from 359 363 rlineto rmdir 885 rmoveto round_num s Scan_failure scanbuf Scanf 3485 scanf Scanning 348 search_backward search_forward 416 seek_command seek_in 282 283 seek_ou
58. refers to the result just computed typically the value of a function application and is valid only if the selected event is an after event typically a function appli cation integer refer to a previously printed value The remaining four forms select part of an expression respectively a record field an array element a string element and the current contents of a reference print variables Print the values of the given variables print can be abbreviated as p 222 display variables Same as print but limit the depth of printing to 1 Useful to browse large data structures without printing them in full display can be abbreviated as d When printing a complex expression a name of the form integer is automatically assigned to its value Such names are also assigned to parts of the value that cannot be printed because the maximal printing depth is exceeded Named values can be printed later on with the commands p integer or d integer Named values are valid only as long as the program is stopped They are forgotten as soon as the program resumes execution set print_depth d Limit the printing of values to a maximal depth of d set print_length Limit the printing of values to at most l nodes printed 16 8 Controlling the debugger 16 8 1 Setting the program name and arguments set program file Set the program name to file set arguments arguments Give arguments as command line arguments for the program A s
59. regexps as ident There is no linearity restriction over as bound variables When a variable is bound more than once the previous rules are to be extended as follows e A variable is a char variable when all its occurrences bind char occurrences in the previous sense e A variable is an option variable when the overall expression can be matched without binding this variable For instance in a as x a _ as x the variable x is of type char whereas in ab as x a _ as x the variable x is of type string option In some cases a sucessful match may not yield a unique set of bindings For instance the matching of aba by the regular expression a ab as x ba a as y may result in binding either x to ab and y to a or x to a and y to ba The automata produced ocamllex on such ambiguous regular expressions will select one of the possible resulting sets of bindings The selected set of bindings is purposely left unspecified 12 2 7 Reserved identifiers All identifiers starting with __ocaml_lex are reserved for use by ocamllex do not use any such identifier in your programs 12 3 Overview of ocamlyacc The ocamlyacc command produces a parser from a context free grammar specification with at tached semantic actions in the style of yacc Assuming the input file is grammar mly executing ocamlyacc options grammar mly produces Caml code for a parser in the file grammar m1 and it
60. t Genarray create kind layout dimensions returns a new big array whose element kind is determined by the parameter kind one of float32 float64 int8_signed etc and whose layout is determined by the parameter layout one of c_layout or fortran_layout The dimensions parameter is an array of integers that indicate the size of the big array in each dimension The length of dimensions determines the number of dimensions of the bigarray For instance Genarray create int32 c_layout 4 6 8 returns a fresh big array of 32 bit integers in C layout having three dimensions the three dimensions being 4 6 and 8 respectively 460 val val val val val val val Big arrays returned by Genarray create are not initialized the initial values of array elements is unspecified Genarray create raises Invalid_arg if the number of dimensions is not in the range 1 to 16 inclusive or if one of the dimensions is negative num_dims a b c t gt int Return the number of dimensions of the given big array dims a b c t gt int arra y Genarray dims a returns all dimensions of the big array a as an array of integers of length Genarray num_dims a nth_dim a b c t gt int gt int Genarray nth_dim a n returns the n th dimension of the big array a The first dimension corresponds to n 0 the second dimension corresponds to n 1 the last dimension to n Genarray num_dims a 1 Ra
61. the actions and possibly some auxiliary functions used in the actions 12 2 2 Naming regular expressions Between the header and the entry points one can give names to frequently occurring regular expressions This is written let ident regexp In regular expressions that follow this declaration the identifier ident can be used as shorthand for regexp Chapter 12 Lexer and parser generators ocamllex ocamlyacc 177 12 2 3 Entry points The names of the entry points must be valid identifiers for Caml values starting with a lowercase letter Similarily the arguments arg arg must be valid identifiers for Caml Each entry point becomes a Caml function that takes n 1 arguments the extra implicit last argument being of type Lexing lexbuf Characters are read from the Lexing lexbuf argument and matched against the regular expressions provided in the rule until a prefix of the input matches one of the rule The corresponding action is then evaluated and returned as the result of the function If several regular expressions match a prefix of the input the longest match rule applies the regular expression that matches the longest prefix of the input is selected In case of tie the regular expression that occurs earlier in the rule is selected However if lexer rules are introduced with the shortest keyword in place of the parse keyword then the shortest match rule applies the shortest prefix of the input is selected In c
62. thus allowing operating on files whose sizes are greater than max_int Operations on file names val unlink string gt unit Removes the named file val rename string gt string gt unit rename old new changes the name of a file from old to new val link string gt string gt unit link source dest creates a hard link named dest to the file named source File permissions and ownership type access_permission R_OK Read permission W_OK Write permission X_OK Execution permission F_OK File exists Flags for the Unix access call val chmod string gt file_perm gt unit Change the permissions of the named file val fchmod file_descr gt file_perm gt unit 384 Change the permissions of an opened file val chown string gt int gt int gt unit Change the owner uid and owner gid of the named file val fchown file_descr gt int gt int gt unit Change the owner uid and owner gid of an opened file val umask int gt int Set the process s file mode creation mask and return the previous mask val access string gt access_permission list gt unit Check that the process has the given permissions over the named file Raise Unix_error otherwise Operations on file descriptors val dup file_descr gt file_descr Return a new file descriptor referencing the same file as the given descriptor val dup2 file_descr gt file_descr gt un
63. usually ctr1 C will not exit the debugger but will terminate the action of any debugger command that is in progress and return to the debugger command level 16 3 Commands A debugger command is a single line of input It starts with a command name which is followed by arguments depending on this name Examples run goto 1000 set arguments argi arg2 A command name can be truncated as long as there is no ambiguity For instance go 1000 is understood as goto 1000 since there are no other commands whose name starts with go For the most frequently used commands ambiguous abbreviations are allowed For instance r stands for run even though there are others commands starting with r You can test the validity of an abbreviation using the help command If the previous command has been successful a blank line typing just RET will repeat it 16 3 1 Getting help The Objective Caml debugger has a simple on line help system which gives a brief description of each command and variable help Print the list of commands help command Give help about the command command Chapter 16 The debugger ocamldebug 217 help set variable help show variable Give help about the variable variable The list of all debugger variables can be obtained with help set help info topic Give help about topic Use help info to get a list of known topics 16 3 2 Accessing the debugger state set variable value Set the debugger variable variable to
64. val minus_one int64 The 64 bit integer 1 val neg int64 gt int64 Unary negation val add int64 gt int64 gt int64 Addition val sub int64 gt int64 gt int64 Subtraction val mul int64 gt int64 gt int64 Multiplication val div int64 gt int64 gt int64 Integer division Raise Division_by_zero if the second argument is zero This division rounds the real quotient of its arguments towards zero as specified for Pervasives 19 2 val rem int64 gt int64 gt int64 Integer remainder If y is not zero the result of Int64 rem x y satisfies the following properties Int64 zero lt Int64 rem x y lt Int64 abs y and x Int64 add Int64 mul Int64 div x y y Int64 rem x y Ify 0 Int64 rem x y raises Division_by_zero val succ int64 gt int64 Successor Int64 succ x is Int64 add x Int64 one val pred int64 gt int64 324 val val val val val val val val val val val val Predecessor Int64 pred x is Int64 sub x Int64 one abs int64 gt int64 Return the absolute value of its argument max_int int64 The greatest representable 64 bit integer 2 1 min_int int64 The smallest representable 64 bit integer 2 logand int64 gt int64 gt int64 Bitwise logical and logor int64 gt int64 gt int64 Bitwise logical or logxor int64 gt int64 gt int64 Bitwise logical exclusive or
65. 1 nameg and names 2 name in expr 135 136 which binds name to the cyclic list 1 2 1 2 and name gt to the cyclic list 2 1 2 1 Informally the class of accepted definitions consists of those definitions where the defined names occur only inside function bodies or as argument to a data constructor More precisely consider the expression let rec name expr and and name expr in expr It will be accepted if each one of expr expr is statically constructive with respect to name name and not immediately linked to any of name namen An expression e is said to be statically constructive with respect to the variables name namen if at least one of the following conditions is true e c has no free occurrence of any of name namen e e is a variable e e has the form fun gt e e has the form function gt e c has the form lazy e c has one of the following forms where each one of expr expr is statically construc tive with respect to name name and expr is statically constructive with respect to name namen xname xnamem let rec xname expr and and xname expr in expro let module in expr constr expr XPlm tag name expr CXPIm expr expr field expr field expr expr with fieldg expry field expr where expr is not immediately
66. 18 3 2 Tuples and records Tuples are represented by pointers to blocks with tag 0 Records are also represented by zero tagged blocks The ordering of labels in the record type declaration determines the layout of the record fields the value associated to the label declared first is stored in field 0 of the block the value associated to the label declared next goes in field 1 and so on As an optimization records whose fields all have static type float are represented as arrays of floating point numbers with tag Double_array_tag See the section below on arrays 18 3 3 Arrays Arrays of integers and pointers are represented like tuples that is as pointers to blocks tagged 0 They are accessed with the Field macro for reading and the modify function for writing Arrays of floating point numbers type float array have a special unboxed more efficient representation These arrays are represented by pointers to blocks with tag Double_array_tag They should be accessed with the Double_field and Store_double_field macros 18 3 4 Concrete types Constructed terms are represented either by unboxed integers for constant constructors or by blocks whose tag encode the constructor for non constant constructors The constant constructors and the non constant constructors for a given concrete type are numbered separately starting from 0 in the order in which they appear in the concrete type declaration Constant constructors are represented
67. 259 B12 B57 350 B61 08 OO 63 a63 F167 get_all_formatter_output_functions 306 get_approx_printing get_copy 3608 get_ellipsis_text get_error_when_null_denominator get_floating_ precision get_formatter_output_functions 305 get_formatter_tag_functions 306 479 get_image 435 get_margin 302 get_mark_tags 305 get_max_boxes 802 get_max_indent 302 get_normalize_ratio get_normalize_ratio_when_printing get_print_tags 305 get_state getaddrinfo getaddrinfo_option getcwd 364 885 getegid getenv 364 376 geteuid getgid getergid getgrnam getgroups 892 gethostbyadadr 399 gethostbyname 399 gethostname 399 getitimer 39 get login 892 getnameinfo 40 getnameinfo_option getpeername 395 getpid getppid getprotobyname 399 getprotobynumber 399 getpwnam getpwuid getservbyname 399 getservbyport 399 getsockname 895 getsockopt getsockopt_float 398 getsockopt_int getsockopt_optint gettimeofday 390 getuid global_replace global_substitute gmt ime 390 480 Graphic_failure 430 Graphics green 31 grid 449 group_beginning group_end group_entry 392 gt_big_int gt_num guard handle_unix_error 376 hash hash_param HashedType Hashtbl ha header_size Help 289 host_entry 398 i 255 ia ignore image in_channel in_channel_length in_channel_of_descr incr 283
68. 3 4 Initializers Let bindings within class definitions are evaluated before the object is constructed It is also possible to evaluate an expression immediately after the object has been built Such code is written as an anonymous hidden method called an initializer Therefore is can access self and the instance variables class printable_point x_init let origin x_init 10 10 in object self val mutable x origin method get_x x method move d x lt x d method print print_int self get_x initializer print_string new point at self print print_newline end class printable_point int gt object val mutable x int method get_x int method move int gt unit method print unit end let p new printable_point 17 new point at 10 val p printable_point lt obj gt Initializers cannot be overridden On the contrary all initializers are evaluated sequentially Ini tializers are particularly useful to enforce invariants Another example can be seen in section 5 1 3 5 Virtual methods It is possible to declare a method without actually defining it using the keyword virtual This method will be provided later in subclasses A class containing virtual methods must be flagged virtual and cannot be instantiated that is no object of this class can be created It still defines type abbreviations treating virtual methods as other methods class virtual abstract_point x_init
69. 336 Failure failwith fast_sort f chmod B83 fchown file 297 file_descr file_exists file_kind file_perm Filename 111 291 357 359 362 368 62 64 466 fill_arc 434 fill_circle fill_ellipse 34 fill_poly fill rect i11Mode 149 filter finalise finalise_release fina BIT B19 B31 B37 B53 FO FAO find_all 358 369 first_chars 19 firstkey 440 flatten 330 358 float float_of_big_int float_of_bits float_of_int float_of_num float_of_string float32 float32_elt float64 457 float64_elt floor 273 floor_num flow_action 404 flush flush_all flush_input 329 flush_queue 404 flush_str_formatter fola fold_left 292 330 357 358 fold_left2 fold_right 292 330 357 B58 fold_right2 for_all for_al12 force force_newline B01 force_val foreground fork Format 299 INDEX TO THE LIBRARY format 283 format _of_string format4 266 formatter formatter_of_buffer formatter_of_out_channel formatter_tag_functions 805 fortran_layout fpclass fprintf 309 frexp from 360 from_channel from_file 348 from_file_bin from_function from_string fscanf fst fstat ftruncate full_init 346 full_major 814 full_split Gc gcd_big_int 412 ge_big_int ge_num Genarray genarray_of_arrayl genarray_of_array2 genarray_of_array3 Genlex get
70. 9 5 Module specifications A specification of a module component in a signature is written module module name module type where module name is the name of the module component and module type its expected type Modules can be nested arbitrarily in particular functors can appear as components of structures and functor types as components of signatures For specifying a module component that is a functor one may write module module name name module type name module type module type instead of module module name functor name module type gt gt module type Module type specifications A module type component of a signature can be specified either as a manifest module type or as an abstract module type An abstract module type specification module type modtype name allows the name modtype name to be implemented by any module type in a matching signature but hides the implementation of the module type to all users of the signature A manifest module type specification module type modtype name module type requires the name modtype name to be implemented by the module type module type in a matching signature but makes the equality between modtype name and module type apparent to all users of the signature Opening a module path The expression open module path in a signature does not specify any components It simply affects the parsing of the following items of the signature allowing components o
71. Cannot find the bytecode file The file that ocamlrun is trying to execute e g the file given as first non option argument to ocamlrun either does not exist or is not a valid executable bytecode file Truncated bytecode file The file that ocamlrun is trying to execute is not a valid executable bytecode file Probably it has been truncated or mangled since created Erase and rebuild it Uncaught exception The program being executed contains a stray exception That is it raises an exception Chapter 10 The runtime system ocamlrun 165 at some point and this exception is never caught This causes immediate termination of the program The name of the exception is printed along with its string and integer argu ments arguments of more complex types are not correctly printed To locate the context of the uncaught exception compile the program with the g option and either run it again under the ocamldebug debugger see chapter 16 or run it with ocamlrun b or with the OCAMLRUNPARAM environment variable set to b 1 Out of memory The program being executed requires more memory than available Either the program builds excessively large data structures or the program contains too many nested function calls and the stack overflows In some cases your program is perfectly correct it just requires more memory than your machine provides In other cases the out of memory message reveals an error in your program non terminating r
72. HH HH HHH HH HH HAF HHH H OH OH OF OF Chapter 5 Advanced examples with classes and modules 85 method tag repr end end 5 3 The subject observer pattern The following example known as the subject observer pattern is often presented in the literature as a difficult inheritance problem with inter connected classes The general pattern amounts to the definition a pair of two classes that recursively interact with one another The class observer has a distinguished method notify that requires two arguments a subject and an event to execute an action class virtual subject event observer object method virtual notify subject gt event gt unit end class virtual a b observer object method virtual notify a gt b gt unit end The class subject remembers a list of observers in an instance variable and has a distinguished method notify_observers to broadcast the message notify to all observers with a particular event e class observer event subject object self val mutable observers observer list method add_observer obs observers lt obs observers method notify_observers e event List iter fun x gt x notify self e observers end class a b subject object c constraint a lt notify c gt b gt unit gt val mutable observers a list method add_observer a
73. Invalid_arg is raised set a b c t gt int gt int gt int gt a gt unit Array3 set a x y v or alternatively a x y z lt v stores the value v at coordinates x y z in a x y and z must be within the bounds of a as described for Bigarray Genarray set 29 1 otherwise Invalid_arg is raised 468 val sub_left Ca b Bigarray c_layout t gt int gt int gt a b Bigarray c_layout t Extract a three dimensional sub array of the given three dimensional big array by restricting the first dimension See Bigarray Genarray sub_left for more details Array3 sub_left applies only to arrays with C layout val sub_right Ca b Bigarray fortran_layout t gt int gt int gt a b Bigarray fortran_layout t Extract a three dimensional sub array of the given three dimensional big array by restricting the second dimension See Bigarray Genarray sub_right for more details Array3 sub_right applies only to arrays with Fortran layout val slice_left_1 Ca b Bigarray c_layout t gt int gt int gt a b Bigarray c_layout Bigarray Array1 t Extract a one dimensional slice of the given three dimensional big array by fixing the first two coordinates The integer parameters are the coordinates of the slice to extract See Bigarray Genarray slice_left 29 1 for more details Array3 slice_left_1 applies only to arrays with C layout val slice_right_1 Ca b Bigarray fortran_l
74. Lex adds colors according to lexical categories e Typecheck verifies typing and memorizes to let one see an expression s type by double clicking on it This is also valid for interfaces If an error occurs the part of the interface preceding the error is computed After typechecking pressing the right button pops up a menu giving the type of the pointed expression and eventually allowing to follow some links e Clear errors dismisses type checker error messages and warnings e Signature shows the signature of the current file after type checking 14 5 Shell When you create a shell a dialog is presented to you letting you choose which command you want to run and the title of the shell to choose it in the Editor The executed subshell is given the current load path e File use a source file or load a bytecode file You may also import the browser s path into the subprocess e History M p and M n browse up and down e Signal C c interrupts and you can also kill the subprocess 194 Chapter 15 The documentation generator ocamldoc This chapter describes OCamldoc a tool that generates documentation from special comments embedded in source files The comments used by OCamldoc are of the form and follow the format described in section 15 2 OCamldoc can produce documentation in various formats HTML ATEX TeXinfo Unix man pages and dot dependency graphs Moreover users can add their own custom genera
75. The LabITk library Tcl Tk GUI interface 449 Application wide commands val update unit gt unit Synchronize display with internal state val appname_get unit gt string val appname_set string gt unit Get or set the application name Dimensions type units Cm of float In of float Mm of float Pix of int Pt of float val pixels units gt int Converts various on screen units to pixels respective to the default display Available units are pixels centimeters inches millimeters and points Widget layout commands type anchor Center E N Ne Nw S Se Sw W type fillMode Both None X Y type side Bottom Left Right Top val pack fafter a Widget widget gt anchor anchor gt before b Widget widget gt expand bool gt fill fillMode gt inside c Widget widget gt ipadx int gt ipady int gt padx int gt pady int gt side side gt d Widget widget list gt unit Pack a widget inside its parent using the standard layout engine val grid column int gt columnspan int gt inside a Widget widget gt ipadx int gt ipady int gt padx int gt pady int gt row int gt rowspan int gt sticky string gt b Widget widget list gt unit Pack a widget inside its parent using the grid layout engine 450 type borderMode
76. a gt Num of b gt b lt fun gt val eval Num of a gt a lt fun gt let plus x y Plus x y let eval2 eval function Plus x y gt eval x eval y Num _ as x gt evali eval x let rec eval x eval2 eval x val plus a gt b gt gt Plus of a b lt fun gt val eval2 a gt int gt lt Num of int Plus of a a gt int lt fun gt val eval lt Num of int Plus of a a as a gt int lt fun gt To make this even more confortable you may use type definitions as abbreviations for or patterns That is if you have defined type myvariant Tagi int Tag2 bool then the pattern myvariant is equivalent to writing Tagi _ int Tag2 _ bool Such abbreviations may be used alone let f function myvariant gt myvariant Tag3 gt Tag3 val f K Tagi of int Tag2 of bool Tag3 gt string lt fun gt or combined with with aliases let g1 function Tagl _ gt Tagi Tag2 _ gt Tag2 val g1 x Tagi of a Tag2 of b gt string lt fun gt let g function myvariant as x gt gi x Tag3 gt Tag3 val g K Tagi of int Tag2 of bool Tag3 gt string lt fun gt 4 2 1 Weaknesses of polymorphic variants After seeing the power of polymorphic variants
77. above considerations can usually be ignored if your lists are not longer than about 10000 elements val length a list gt int Return the length number of elements of the given list val hd a list gt a Return the first element of the given list Raise Failure hd if the list is empty val tl a list gt a list Return the given list without its first element Raise Failure t1 if the list is empty val nth a list gt int gt a Return the n th element of the given list The first element head of the list is at position 0 Raise Failure nth if the list is too short val rev a list gt a list List reversal val append a list gt a list gt a list Catenate two lists Same function as the infix operator Not tail recursive length of the first argument The operator is not tail recursive either val rev_append a list gt a list gt a list List rev_append 11 12 reverses 11 and concatenates it to 12 This is equivalent to List rev 20 17 11 12 but rev_append is tail recursive and more efficient val concat a list list gt a list Concatenate a list of lists The elements of the argument are all concatenated together in the same order to give the result Not tail recursive length of the argument length of the longest sub list 330 val flatten a list list gt a list Same as concat Not tail recursive length
78. adds the subdirectory labltk of the standard library to the search path Directories can also be added to the search path once the toplevel is running with the directory directive section 9 2 nolabels Ignore non optional labels in types Labels cannot be used in applications and parameter order becomes strict principal Check information path during type checking to make sure that all types are derived in a principal way All programs accepted in principal mode are also accepted in default mode with equivalent types rectypes Allow arbitrary recursive types during type checking By default only recursive types where the recursion goes through an object type are supported unsafe See the corresponding option for ocamlc chapter 8 Turn bound checking off on array and string accesses the v i and s i constructs Programs compiled with unsafe are therefore slightly faster but unsafe anything can happen if the program accesses an array or string outside of its bounds w warning list Enable or disable warnings according to the argument warning list Unix The following environment variables are also consulted 156 LC_CTYPE If set to iso_8859_1 accented characters from the ISO Latin 1 character set in string and character literals are printed as is otherwise they are printed as decimal escape sequences ddd TERM When printing error messages the toplevel system attempts to underline visually the loca
79. and 127 are interpreted following the ASCII standard The current implementation interprets character codes between 128 and 255 following the ISO 8859 1 standard Character strings String values are finite sequences of characters The current implementation supports strings con taining up to 274 5 characters 16777211 characters on 64 bit platforms the limit is 257 9 6 2 2 Tuples Tuples of values are written v1 Un standing for the n tuple of values v to vn The current implementation supports tuple of up to 27 1 elements 4194303 elements 96 6 2 3 Records Record values are labeled tuples of values The record value written field v1 field un associates the value v to the record field field for i 1 n The current implementation supports records with up to 2 1 fields 4194308 fields 6 2 4 Arrays Arrays are finite variable sized sequences of values of the same type The current implementation supports arrays containing to 27 1 elements 4194303 elements on 64 bit platforms the limit is 254 1 6 2 5 Variant values Variant values are either a constant constructor or a pair of a non constant constructor and a value The former case is written constr the latter case is written constr v where v is said to be the argument of the non constant constructor constr The following constants are treated like built in constant constructors Constant Constructor false
80. and two methods get_x and move The initial value of the instance variable is 0 The variable x is declared mutable so the method move can change its value class point object val mutable x 0 method get_x x method move d x lt x d H H H H end class point object val mutable x int method get_x int method move int gt unit end We now create a new point p instance of the point class let p new point val p point lt obj gt Note that the type of p is point This is an abbreviation automatically defined by the class definition above It stands for the object type lt get_x int move int gt unit gt listing the methods of class point along with their types We now invoke some methods to p p get_x int 0 p move 3 unit QO p get_x int 3 33 34 The evaluation of the body of a class only takes place at object creation time Therefore in the following example the instance variable x is initialized to different values for two different objects let xO ref 0 val xO int ref contents 0 class point object val mutable x incr x0 x0 method get_x x method move d x lt x d end class point object val mutable x int method get_x int method move int gt unit end new point get_x int 1 new point get_x int 2 The class point can also be abstracted over the initial values of
81. another set socket socket Use socket for communication with the program socket can be either a file name or an Internet port specification host port where host is a host name or an Internet address in dot notation and port is a port number on the host 224 On the debugged program side the socket name is passed through the CAML_DEBUG_SOCKET environment variable 16 8 7 Fine tuning the debugger Several variables enables to fine tune the debugger Reasonable defaults are provided and you should normally not have to change them set processcount count Set the maximum number of checkpoints to count More checkpoints facilitate going far back in time but use more memory and create more Unix processes As checkpointing is quite expensive it must not be done too often On the other hand backward execution is faster when checkpoints are taken more often In particular backward single stepping is more responsive when many checkpoints have been taken just before the current time To fine tune the checkpointing strategy the debugger does not take checkpoints at the same frequency for long displacements e g run and small ones e g step The two variables bigstep and smallstep contain the number of events between two checkpoints in each case set bigstep count Set the number of events between two checkpoints for long displacements set smallstep count Set the number of events between two checkpoints for small displacements The
82. array S_port int s_proto string Structure of entries in the services database val gethostname unit gt string Return the name of the local host val gethostbyname string gt host_entry Find an entry in hosts with the given name or raise Not_found val gethostbyaddr inet_addr gt host_entry Find an entry in hosts with the given address or raise Not_found val getprotobyname string gt protocol_entry Find an entry in protocols with the given name or raise Not_found val getprotobynumber int gt protocol_entry Find an entry in protocols with the given protocol number or raise Not_found val getservbyname string gt string gt service_entry Find an entry in services with the given name or raise Not_found val getservbyport int gt string gt service_entry Find an entry in services with the given service number or raise Not_found type addr_info ai_family socket_domain Socket domain ai_socktype socket_type Socket type ai_protocol int Socket protocol number ai_addr sockaddr Address ai_canonname string Canonical host name 399 400 Address information returned by Unix getaddrinfo type getaddrinfo_option AI_FAMILY of socket_domain Impose the given socket domain AI_SOCKTYPE of socket_type Impose the given socket type AI_PROTOCOL of int Impose the given protocol AI_NUMERICHOST Do not call name resolver exp
83. array of arrays with first dimension dimx and second dimension dimy All the elements of this new matrix are initially physically equal to e The element x y of a matrix m is accessed with the notation m x y Raise Invalid_argument if dimx or dimy is negative or greater than Sys max_array_length If the value of e is a floating point number then the maximum size is only Sys max_array_length 2 val create_matrix int gt int gt a gt a array array Deprecated Array create_matrix is an alias for Array make_matrix 20 2 val append a array gt a array gt a arra PP y y Chapter 20 The standard library 291 val val val val val val val val val val Array append v1 v2 returns a fresh array containing the concatenation of the arrays v1 and v2 concat a array list gt a array Same as Array append but concatenates a list of arrays sub a array gt int gt int gt a array Array sub a start len returns a fresh array of length len containing the elements number start to start len 1 of array a Raise Invalid_argument Array sub if start and len do not designate a valid subarray of a that is if start lt 0 or len lt 0 or start len gt Array length a copy a array gt a array Array copy a returns a copy of a that is a fresh array containing the same elements as a fill a array gt int gt int gt a gt
84. as described in the manual for ocamlc chapter B 167 168 Arguments ending in cmx are taken to be compiled object code These files are linked together along with the object files obtained by compiling m1 arguments if any and the Caml standard library to produce a native code executable program The order in which cmx and ml arguments are presented on the command line is relevant compilation units are initialized in that order at run time and it is a link time error to use a component of a unit before having initialized it Hence a given x cmx file must come before all cmx files that refer to the unit z Arguments ending in cmxa are taken to be libraries of object code Such a library packs in two files lib cmxa and lib a a set of object files cmx o files Libraries are build with ocamlopt a see the description of the a option below The object files contained in the library are linked as regular cmx files see above in the order specified when the library was built The only difference is that if an object file contained in a library is not referenced anywhere in the program then it is not linked in Arguments ending in c are passed to the C compiler which generates a o object file This object file is linked with the program Arguments ending in o a or so obj 1ib and d11 under Windows are assumed to be C object files and libraries They are linked with the program The output of the linking phase
85. b event wrap ev fn returns the event that performs the same communications as ev then applies the post processing function fn on the return value val wrap_abort a event gt unit gt unit gt a event wrap_abort ev fn returns the event that performs the same communications as ev but if it is not selected the function fn is called after the synchronization val guard unit gt a event gt a event guard fn returns the event that when synchronized computes fn and behaves as the resulting event This allows to compute events with side effects at the time of the synchronization operation val sync a event gt a Synchronize on an event offer all the communication possibilities specified in the event to the outside world and block until one of the communications succeed The result value of that communication is returned val select a event list gt a Synchronize on an alternative of events select evl is shorthand for sync choose ev1 val poll a event gt a option Non blocking version of Event sync 24 4 offer all the communication possibilities specified in the event to the outside world and if one can take place immediately perform it and return Some r where r is the result value of that communication Otherwise return None without blocking 24 5 Module ThreadUnix Thread compatible system calls The functionality of this module has been merged back
86. be flushed at the end of pretty printing using pp_print_flush or pp_print_newline to display all the pending material val stdbuf Buffer t The string buffer in which str_formatter writes val str_formatter formatter A formatter to use with formatting functions below for output to the stdbuf string buffer str_formatter is defined as formatter_of_buffer stdbuf val flush_str_formatter unit gt string Returns the material printed with str_formatter flushes the formatter and resets the corresponding buffer val make_formatter string gt int gt int gt unit gt unit gt unit gt formatter make_formatter out flush returns a new formatter that writes according to the output function out and the flushing function flush Hence a formatter to the out channel oc is returned by make_formatter output oc fun gt flush oc 308 Basic functions to use with formatters val pp_open_hbox formatter gt unit gt unit val pp_open_vbox formatter gt int gt unit val pp_open_hvbox formatter gt int gt unit val pp_open_hovbox formatter gt int gt unit val pp_open_box formatter gt int gt unit val pp_close_box formatter gt unit gt unit val pp_open_tag formatter gt string gt unit val pp_close_tag formatter gt unit gt unit val pp_print_string formatter gt string gt unit val pp_print_as formatter gt int gt string gt unit val pp_print_i
87. be given on all three invocations of ocamlmklib because they are needed at different times depending on whether shared libraries are supported 262 Part IV The Objective Caml library 263 Chapter 19 The core library This chapter describes the Objective Caml core library which is composed of declarations for built in types and exceptions plus the module Pervasives that provides basic operations on these built in types The Pervasives module is special in two ways e It is automatically linked with the user s object code files by the ocamlc command chapter 8 e It is automatically opened when a compilation starts or when the toplevel system is launched Hence it is possible to use unqualified identifiers to refer to the functions pro vided by the Pervasives module without adding a open Pervasives directive Conventions The declarations of the built in types and the components of module Pervasives are printed one by one in typewriter font followed by a short comment All library modules and the components they provide are indexed at the end of this report 19 1 Built in types and predefined exceptions The following built in types and predefined exceptions are always defined in the compilation envi ronment but are not part of any module As a consequence they can only be referred by their short names Built in types type int The type of integer numbers type char The type of characters type strin
88. by unboxed integers equal to the constructor number Non constant constructors declared with a n tuple as argument are represented by a block of size n tagged with the constructor number the n fields contain the components of its tuple argument Other non constant constructors are represented by a block of size 1 tagged with the constructor number the field 0 contains the value of the constructor argument Example 240 Constructed term Representation O Val_int 0 false Val_int 0 true Val_int 1 Val_int 0 h t Block with size 2 and tag 0 first field con tains h second field t As a convenience caml mlvalues h defines the macros Val_unit Val_false and Val_true to refer to false and true 18 3 5 Objects Objects are represented as zero tagged blocks The first field of the block refers to the object class and associated method suite in a format that cannot easily be exploited from C The remaining fields of the object contain the values of the instance variables of the object Instance variables are stored in the order in which they appear in the class definition taking inherited classes into account One may extract a public method from an object using the C function caml_get_public_method declared in lt caml mlvalues h gt Since public method tags are hashed in the same way as variant tags and methods are functions taking self as first argument if you want to do the method call foo bar
89. can be used in the whole expression except for inheritance It can also be used for inheritance but only in the definitions that follow its own A class binding binds the class name class name to the value of expression class expr It also binds the class type class name to the type of the class and defines two type abbreviations class name and class name The first one is the type of objects of this class while the second is more general as it unifies with the type of any object belonging to a subclass see section 6 4 Virtual class A class must be flagged virtual if one of its methods is virtual that is appears in the class type but is not actually defined Objects cannot be created from a virtual class Type parameters The class type parameters correspond to the ones of the class type and of the two type abbreviations defined by the class binding They must be bound to actual types in the class definition using type constraints So that the abbreviations are well formed type variables of the inferred type of the class must either be type parameters or be bound in the constraint clause 6 9 4 Class specification class specification class class spec and class spec class spec virtual type parameters class name class type This is the counterpart in signatures of class definitions A class specification matches a class definition if they have the same type parameters and their types match 6 9 5 Class type
90. capitalization of the identifier whether the first letter of the identifier is in lowercase written lowercase ident below or in uppercase written capitalized ident Underscore is considered a lowercase letter for this purpose Naming objects value name operator name infix op constr name label name tag name typeconstr name field name module name modtype name class name inst var name method name lowercase ident operator name prefix symbol infix op infix symbol or amp mod land lor lxor 1s1 1sr asr capitalized ident lowercase ident capitalized ident lowercase ident lowercase ident capitalized ident ident lowercase ident lowercase ident lowercase ident 98 As shown above prefix and infix symbols as well as some keywords can be used as value names provided they are written between parentheses The capitalization rules are summarized in the table below Name space Case of first letter Values lowercase Constructors uppercase Labels lowercase Variant tags uppercase Exceptions uppercase Type constructors lowercase Record fields lowercase Classes lowercase Instance variables lowercase Methods lowercase Modules uppercase Module types any Note on variant tags the current implementation accepts lowercase variant tags in addition to uppercase variant tags but we suggest you avoid lowercase variant tags for portability and compatibility with future O
91. comparison operators lt gt lt gt lt gt and compare The C function should return 0 if the data contained in the two blocks are structurally equal a negative integer if the data from the first block is less than the data from the second block and a positive integer if the data from the first block is greater than the data from the second block Note You must use CAMLparam to declare v1 and v2 and CAMLreturn to return the result The compare field can be set to custom_compare_default this default comparison function simply raises Failure e long hash value v The hash field contains a pointer to a C function that is called whenever Caml s generic hash operator see module Hashtb1 is applied to a custom block The C function can return an arbitrary long integer representing the hash value of the data contained in the given custom block The hash value must be compatible with the compare function in the sense that two structurally equal data that is two custom blocks for which compare returns 0 must have the same hash value Note You must use CAMLparam to declare v and CAMLreturn to return the result The hash field can be set to custom_hash_default in which case the custom block is ignored during hash computation e void serialize value v unsigned long wsize_32 unsigned long wsize_64 The serialize field contains a pointer to a C function that is called whenever the cus tom block needs to be serializ
92. compiler unless the s option is in effect The type part is an arbitrary Caml type expression except that all type constructor names must be fully qualified as explained above for token Aleft symbol symbol right symbol symbol Z nonassoc symbol symbol Associate precedences and associativities to the given symbols All symbols on the same line are given the same precedence They have higher precedence than symbols declared before in a Zleft 4right or Znonassoc line They have lower precedence than symbols declared after in a Zleft right or 4nonassoc line The symbols are declared to associate to the left Aleft to the right Aright or to be non associative j nonassoc The symbols are usually tokens They can also be dummy nonterminals for use with the prec directive inside the rules The precedence declarations are used in the following way to resolve reduce reduce and shift reduce conflicts e Tokens and rules have precedences By default the precedence of a rule is the precedence of its rightmost terminal You can override this default by using the prec directive in the rule e A reduce reduce conflict is resolved in favor of the first rule in the order given by the source file and ocamlyacc outputs a warning e A shift reduce conflict is resolved by comparing the precedence of the rule to be reduced with the precedence of the token to be shifted If the precedence of the rule is higher then the rule wil
93. containing all elements of s except x If x was not in s s is returned unchanged union t gt t gt t Set union inter t gt t gt t Set intersection diff t gt t gt t Set difference compare t gt t gt int Total ordering between sets Can be used as the ordering function for doing sets of sets equal t gt t gt bool equal s1 s2 tests whether the sets s1 and s2 are equal that is contain equal elements subset t gt t gt bool subset s1 s2 tests whether the set s1 is a subset of the set s2 304 val val val val val val val val val val val iter elt gt unit gt t gt unit iter f s applies f in turn to all elements of s The elements of s are presented to f in increasing order with respect to the ordering over the type of the elements fold elt gt a gt a gt t gt a gt a fold f s a computes f xN f x2 f x1 a where xl xN are the elements of s in increasing order for_all elt gt bool gt t gt bool for_all p s checks if all elements of the set satisfy the predicate p exists elt gt bool gt t gt bool exists p s checks if at least one element of the set satisfies the predicate p filter elt gt bool gt t gt t filter p s returns the set of all elements in s that satisfy predicate p partition elt gt bool gt t gt t t partition p s retu
94. define a generator class in several modules which are defined in several files file1 ml i file2 m1 i fileN m1 i A cma library file must be created including all these files The following commands create the custom cma file from files file1 m1 i fileN ml i ocamlc I ocamldoc c file1 ml i ocamlc I ocamldoc c file2 ml i ocamlc I ocamldoc c fileN ml i ocamlc o custom cma a filel cmo file2 cmo fileN cmo Chapter 15 The documentation generator ocamldoc 213 Then the following command uses custom cma as custom generator ocamldoc g custom cma other options source files Again it is important not to give the html or any other option selecting a built in generator to ocamldoc which would result in using this generator instead of the one you just loaded 214 Chapter 16 The debugger ocamldebug This chapter describes the Objective Caml source level replay debugger ocamldebug Unix The debugger is available on Unix systems that provide BSD sockets Windows The debugger is available under the Cygwin port of Objective Caml but not under the native Win32 ports 16 1 Compiling for debugging Before the debugger can be used the program must be compiled and linked with the g option all cmo and cma files that are part of the program should have been created with ocamlc g and they must be linked together with ocamlc g Compiling with g entails no penalty on the running time of prog
95. definitions classtype definition class type classtype def and classtype def classtype def virtual type parameters class name class body type A class type definition class class name class body type defines an abbreviation class name for the class body type class body type As for class definitions two type abbreviations class name and class name are also defined The definition can be parameterized by some type parameters If any method in the class type body is virtual the definition must be flagged virtual Two class type definitions match if they have the same type parameters and the types they expand to match 126 6 10 Module types module specifications Module types are the module level equivalent of type expressions they specify the general shape and type properties of modules module type modtype path sig specification end functor module name module type gt module type module type with mod constraint and mod constraint module type specification val value name typexpr external value name typexpr external declaration type definition exception constr decl class specification classtype definition module module name module type module module name module name module type module type module type modtype name module type modtype name module type open module path include module type mod constraint type type parameters typeconstr typ
96. first in the try expression is selected If none of the patterns matches the value of expr the exception value is raised again thereby transparently passing through the try construct 6 7 3 Operations on data structures Products The expression expr expr evaluates to the n tuple of the values of expressions expr to expr The evaluation order for the subexpressions is not specified Variants The expression constr expr evaluates to the variant value whose constructor is constr and whose argument is the value of expr For lists some syntactic sugar is provided The expression expr exprs stands for the con structor applied to the argument expr expr and therefore evaluates to the list whose head is the value of expr and whose tail is the value of expry The expression expr 3 expr is equivalent to expr expr J and therefore evaluates to the list whose elements are the values of expr to expr Polymorphic variants The expression tag name expr evaluates to the variant value whose tag is tag name and whose argument is the value of expr Records The expression field expr field expr evaluates to the record value field v 3 field Vn where v is the value of expr for i 1 n The fields field 114 to field must all belong to the same record types all fields belonging to this record type must appear exactly once in the record expressio
97. floor_num n returns the largest integer smaller or equal to n val round_num num gt num round_num n returns the integer closest to n In case of ties rounds off zero val ceiling_num num gt num ceiling num n returns the smallest integer bigger or equal to n val sign_num num gt int Return 1 0 or 1 according to the sign of the argument Comparisons between numbers val num gt num gt bool val lt num gt num gt bool val gt num gt num gt bool val lt num gt num gt bool val gt num gt num gt bool val lt gt num gt num gt bool val eq_num num gt num gt bool val lt_num num gt num gt bool 410 val val val val val val le_num num gt num gt bool gt_num num gt num gt bool ge_num num gt num gt bool compare_num num gt num gt int Return 1 0 or 1 if the first argument is less than equal to or greater than the second argument max_num num gt num gt num Return the greater of the two arguments min_num num gt num gt num Return the smaller of the two arguments Coercions with strings val val val val string_of_num num gt string Convert a number to a string using fractional notation approx_num_fix int gt num gt string See Num approx_num_exp approx_num_exp int gt num gt string Approximate a number by a decimal T
98. following commands display information on checkpoints and events info checkpoints Print a list of checkpoints info events module Print the list of events in the given module the current module by default 16 8 8 User defined printers Just as in the toplevel system section 9 2 the user can register functions for printing values of certain types For technical reasons the debugger cannot call printing functions that reside in the program being debugged The code for the printing functions must therefore be loaded explicitly in the debugger load_printer file name Load in the debugger the indicated cmo or cma object file The file is loaded in an envi ronment consisting only of the Objective Caml standard library plus the definitions provided by object files previously loaded using load_printer If this file depends on other object files not yet loaded the debugger automatically loads them if it is able to find them in the search path The loaded file does not have direct access to the modules of the program being debugged Chapter 16 The debugger ocamldebug 225 install_printer printer name Register the function named printer name a value path as a printer for objects whose types match the argument type of the function That is the debugger will call printer name when it has such an object to print The printing function printer name must use the Format library module to produce its output otherwise its output will no
99. for the link itself val fstat file_descr gt stats Return the informations for the file associated with the given descriptor 382 File operations on large files module LargeFile sig val lseek Unix file_descr gt int64 gt Unix seek_command gt int64 val truncate string gt int64 gt unit val ftruncate Unix file_descr gt int64 gt unit type stats st_dev int Device number st_ino int Inode number st_kind Unix file_kind Kind of the file st_perm Unix file_perm Access rights st_nlink int Number of links st_uid int User id of the owner st_gid int Group ID of the file s group st_rdev int Device minor number st_size int64 Size in bytes st_atime float Last access time st_mtime float Last modification time st_ctime float Last status change time Chapter 21 The unix library Unix system calls 383 val stat string gt stats val lstat string gt stats val fstat Unix file_descr gt stats end File operations on large files This sub module provides 64 bit variants of the functions Unix lseek for positioning a file descriptor Unix truncate and Unix ftruncate 21 1 for changing the size of a file and Unix stat 21 1 Unix 1lstat and Unix fstat for obtaining information on files These alternate functions represent positions and sizes by 64 bit integers type int64 instead of regular integers type int
100. format strings included for backward compatibility with earlier releases of Objective Caml a is the type of the parameters of the format c is the result type for the printf style function and b is the type of the first argument given to a and t printing functions 284 val string_of_format a b c d format4 gt string Converts a format string into a string val format_of_string Ca b c d format4 gt Ca b c d format4 format_of_string s returns a format string read from the string literal s val 77 Ca b c d format4 gt Cd b c e format4 gt a b c e format4 f1 f2 catenates formats f1 and f2 The result is a format that accepts arguments from f1 then arguments from f2 Program termination val exit int gt a Terminate the process returning the given status code to the operating system usually 0 to indicate no errors and a small positive integer to indicate failure All open output channels are flushed with flush_all An implicit exit 0 is performed each time a program terminates normally An implicit exit 2 is performed if the program terminates early because of an uncaught exception val at_exit unit gt unit gt unit Register the given function to be called at program termination time The functions registered with at_exit will be called when the program executes Pervasives exit 19 2 or terminates eithe
101. from the C side you should call callback caml_get_public_method foo hash_variant bar foo 18 3 6 Variants Like constructed terms values of variant types are represented either as integers for variants without arguments or as blocks for variants with an argument Unlike constructed terms variant constructors are not numbered starting from 0 but identified by a hash value a Caml integer as computed by the C function hash_variant declared in lt caml mlvalues h gt the hash value for a variant constructor named say VConstr is hash_variant VConstr The variant value VConstr is represented by hash_variant VConstr The variant value vConstr v is represented by a block of size 2 and tag 0 with field number 0 containing hash_variant VConstr and field number 1 containing v Unlike constructed values variant values taking several arguments are not flattened That is VConstr v v is represented by a block of size 2 whose field number 1 contains the representation of the pair v v but not as a block of size 3 containing v and v in fields 1 and 2 18 4 Operations on values 18 4 1 Kind tests e Is_long v is true if value v is an immediate integer false otherwise e Is_block v is true if value v is a pointer to a block and false if it is an immediate integer Chapter 18 Interfacing C with Objective Caml 241 18 4 2 Operations on integers Val_long returns the value encoding the long i
102. fun gt You can avoid such risks by annotating the definition itself let f abc gt string function As gt A abc gt other Warning this match case is unused val f abc gt string lt fun gt Chapter 5 Advanced examples with classes and modules Chapter written by Didier R my In this chapter we show some larger examples using objects classes and modules We review many of the object features simultaneously on the example of a bank account We show how modules taken from the standard library can be expressed as classes Lastly we describe a programming pattern know of as virtual types through the example of window managers 5 1 Extended example bank accounts In this section we illustrate most aspects of Object and inheritance by refining debugging and specializing the following initial naive definition of a simple bank account We reuse the module Euro defined at the end of chapter B let euro new Euro c val euro float gt Euro c lt fun gt let zero euro 0 val zero Euro c lt obj gt let neg x x times 1 val neg lt times float gt a gt gt a lt fun gt class account object val mutable balance zero method balance balance method deposit x balance lt balance plus x method withdraw x if x leq balance then balance lt balance plus neg x x else zero end class account object
103. functions val set_state State t gt unit Set the state of the generator used by the basic functions 348 20 27 Module Scanf Formatted input functions module Scanning sig type scanbuf val val val val val val val The type of scanning buffers A scanning buffer is the argument passed to the scanning functions used by the scanf family of functions The scanning buffer holds the current state of the scan plus a function to get the next char from the input and a token buffer to store the string matched so far stdib scanbuf The scanning buffer reading from stdin stdib is equivalent to Scanning from_channel stdin from_string string gt scanbuf Scanning from_string s returns a scanning buffer which reads from the given string Reading starts from the first character in the string The end of input condition is set when the end of the string is reached from_file string gt scanbuf Bufferized file reading in text mode The efficient and usual way to scan text mode files in effect from_file returns a buffer that reads characters in large chunks rather than one character at a time as buffers returned by from_channel do Scanning from_file fname returns a scanning buffer which reads from the given file fname in text mode from_file_bin string gt scanbuf Bufferized file reading in binary mode from_function unit gt char gt scanbuf Scanning from_function f re
104. given version of Objective Caml 280 val val val val val val val output_value out_channel gt a gt unit Write the representation of a structured value of any type to a channel Circularities and sharing inside the value are detected and preserved The object can be read back by the function Pervasives input _value 19 2 See the description of module Marshal for more information Pervasives output_value 19 2 is equivalent to Marshal to_channe1 20 19 with an empty list of flags seek_out out_channel gt int gt unit seek_out chan pos sets the current writing position to pos for channel chan This works only for regular files On files of other kinds such as terminals pipes and sockets the behavior is unspecified pos_out out_channel gt int Return the current writing position for the given channel Does not work on channels opened with the Open_append flag returns unspecified results out_channel_length out_channel gt int Return the size number of characters of the regular file on which the given channel is opened If the channel is opened on a file that is not a regular file the result is meaningless close_out out_channel gt unit Close the given channel flushing all buffered write operations Output functions raise a Sys_error exception when they are applied to a closed output channel except close_out and flush which do nothing when applied to an already closed c
105. gt a gt b gt b gt b end class intlist l object self int iterator method empty 1 method fold f accu List fold_left f accu 1 end Note here the self int iterator idiom which ensures that this object implements the interface iterator Polymorphic methods are called in exactly the same way as normal methods but you should be aware of some limitations of type inference Namely a polymorphic method can only be called if its type is known at the call site Otherwise the method will be assumed to be monomorphic and given an incompatible type let sum lst lst fold fun x y gt x y 0 val sum lt fold int gt int gt int gt int gt a gt gt a lt fun gt sum 1 This expression has type intlist but is here used with type lt fold int gt int gt int gt int gt a gt Types for method fold are incompatible The workaround is easy you should put a type constraint on the parameter let sum lst _ iterator lst fold fun x y gt xty 0 val sum int iterator gt int lt fun gt Of course the constraint may also be an explicit method type Only occurences of quantified variables are required Chapter 3 Objects in Caml 49 let sum lst lst lt fold a Ca gt _ gt a gt a gt a gt fold 0 val sum lt fold a a gt int gt a gt a gt
106. hashtable lookup to separate keywords from identifiers let keyword_table Hashtbl create 53 let _ List iter fun kwd tok gt Hashtbl add keyword_table kwd tok keywordi KWD1 keyword2 KWD2 keyword100 KWD100 rule token parse A Z a z PASZ o aa 0g _ as id try Hashtbl find keyword_table id with Not_found gt IDENT id ocamllex Position memory overflow too many bindings The deterministic automata generated by ocamllex maintains a table of positions inside the scanned lexer buffer The size of this table is limited to at most 255 cells This error should not show up in normal situations 186 Chapter 13 Dependency generator ocamldep The ocamldep command scans a set of Objective Caml source files m1 and m1i files for references to external compilation units and outputs dependency lines in a format suitable for the make utility This ensures that make will compile the source files in the correct order and recompile those files that need to when a source file is modified The typical usage is ocamldep options mli ml gt depend where mli ml expands to all source files in the current directory and depend is the file that should contain the dependencies See below for a typical Makefile Dependencies are generated both for compiling with the bytecode compiler ocamlc and with the native code compiler ocamlopt 13 1 Options The following command line option is reco
107. here progi should be compiled to bytecode and is composed of three units modi mod2 and mod3 The list of object files for progi PROG1_OBJS mod1 cmo mod2 cmo mod3 cmo progi PROG1_OBJS OCAMLC o prog1 OCAMLFLAGS PROG1_OBJS prog2 should be compiled to native code and is composed of two units mod4 and modbd The list of object files for prog2 PROG2_OBJS mod4 cmx mod5 cmx prog2 PROG2_OBJS OCAMLOPT o prog2 OCAMLFLAGS PROG2_O0BJS Common rules OUFFIXES ml mli cmo cmi cmx ml cmo OCAMLC OCAMLFLAGS c lt mli cmi OCAMLC OCAMLFLAGS c lt ml cmx OCAMLOPT OCAMLOPTFLAGS c lt Clean up clean rm f progi prog2 rm f cm iox Chapter 13 Dependency generator ocamldep 189 Dependencies depend OCAMLDEP INCLUDES mli ml gt depend include depend 190 Chapter 14 The browser editor ocamlbrowser This chapter describes OCamlBrowser a source and compiled interface browser written using LablTk This is a useful companion to the programmer Its functions are e navigation through Objective Caml s modules using compiled interfaces e source editing type checking and browsing e integrated Objective Caml shell running as a subprocess 14 1 Invocation The browser is started by the command ocamlbrowser as follows ocamlbrowser options The following command line options are recognized by ocamlbrow
108. ic buf pos len reads len characters from channel ic storing them in string buf starting at character number pos Raise End_of_file if the end of file is reached before len characters have been read Raise Invalid_argument really_input if pos and len do not designate a valid substring of buf input_byte in_channel gt int Same as Pervasives input_char 19 2 but return the 8 bit integer representing the character Raise End_of_file if an end of file was reached input_binary_int in_channel gt int Read an integer encoded in binary format 4 bytes big endian from the given input channel See Pervasives output_binary_int 19 2 Raise End_of_file if an end of file was reached while reading the integer 282 val val val val val val val input_value in_channel gt a Read the representation of a structured value as produced by Pervasives output_value 19 2 and return the corresponding value This function is identical to Marshal from_channel 20 19 see the description of module Marshal for more information in particular concerning the lack of type safety seek_in in_channel gt int gt unit seek_in chan pos sets the current reading position to pos for channel chan This works only for regular files On files of other kinds the behavior is unspecified pos_in in_channel gt int Return the current reading position for the given channel in_channel_length in_channel gt int Retu
109. in or to as label Formal parameters and arguments are matched according to their respective labeld the absence of label being interpreted as the empty label This allows commuting arguments in applications One can also partially apply a function on any argument creating a new function of the remaining parameters let f x y x ys val f x int gt y int gt int lt fun gt f y 2 x 3 int 1 ListLabels fold_left a gt b gt a gt init a gt b list gt a lt fun gt ListLabels fold_left 1 2 3 init 0 f int 6 ListLabels fold_left init 0 f int gt a gt int gt a list gt int lt fun gt If in a function several arguments bear the same label or no label they will not commute among themselves and order matters But they can still commute with other arguments let hline x x1 x x2 y x1 x2 y val hline x a gt x b gt y c gt a b c lt fun gt hline x 3 y 2 x 5 int int int 3 5 2 As an exception to the above parameter matching rules if an application is total labels may be omitted In practice most applications are total so that labels can be omitted in applications f 3 2 int 1 ListLabels map succ 1 2 3 int list 2 3 4 But beware that functions like ListLabels fold_left whose result type is a type variable will
110. in variant type exn of exception values The constructors are declared as for a definition of a variant type The form exception constr name of typexpr generates a new exception distinct from all other exceptions in the system The form exception constr name constr gives an alternate name to an existing exception 6 9 Classes Classes are defined using a small language similar to the module language 6 9 1 Class types Class types are the class level equivalent of type expressions they specify the general shape and type properties of classes 120 class type class body type label name typexpr gt class type class body type object typexpr class field spec end class path typexpr typexpr class path inherit class type val mutable inst var name typexpr method private method name poly typexpr method private virtual method name poly typexpr class field spec constraint typexpr typexpr Simple class expressions The expression class path is equivalent to the class type bound to the name class path Similarly the expression typexpr typexpr class path is equivalent to the parametric class type bound to the name class path in which type parameters have been instanciated to respectively typexpr typexpr Class function type The class type expression typexpr gt class type is the type of class functions functions from values to classes that take as argu
111. int gt a gt unit module List sig val val val val val val length a list gt int hd a list gt a tl a list gt a list nth a list gt int gt a rev a list gt a list append a list gt a list gt a list 358 val val val val val val val val val val val val val val val val val val val val val val val val val val val val val val val val val val val rev_append a list gt a list gt a list concat a list list gt a list flatten a list list gt a list iter f a gt unit gt a list gt unit map f a gt b gt a list gt b list rev_map f a gt b gt a list gt b list fold_left f a gt b gt a gt init a gt b list gt a fold_right f a gt b gt b gt a list gt init b gt b iter2 f a gt b gt unit gt a list gt b list gt unit map2 f a gt tb gt c gt a list gt b list gt c list rev_map2 f a gt b gt c gt a list gt b list gt c list fold_left2 Ca gt b gt c gt a gt init a gt b list gt c list gt a fold_right2 Ca gt b gt c gt c gt a list gt b list gt init c gt c for_all f a gt bool gt a list gt boo
112. into the Unix 21 1 module Threaded programs can now call the functions from module Unix 21 1 directly and still get the correct behavior block the calling thread if required but do not block all threads in the process Thread compatible system calls Process handling val execv string gt string array gt unit val execve string gt string array gt string array gt unit val execvp string gt string array gt unit val wait unit gt int Unix process_status val waitpid Unix wait_flag list gt int gt int Unix process_status val system string gt Unix process_status Chapter 24 The threads library 427 Basic input output val read Unix file_descr gt string gt int gt int gt int val write Unix file_descr gt string gt int gt int gt int Input output with timeout val timed_read Unix file_descr gt string gt int gt int gt float gt int See ThreadUnix timed_write val timed_write Unix file_descr gt string gt int gt int gt float gt int Behave as ThreadUnix read 24 5 and ThreadUnix write 24 5 except that Unix_error ETIMEDOUT _ _ is raised if no data is available for reading or ready for writing after d seconds The delay d is given in the fifth argument in seconds Polling val select Unix file_descr list gt Unix file_descr list gt Unix file_descr list gt float gt Unix file_descr list Unix file_descr list
113. is a regular Unix executable file It does not need ocamlrun to run 11 2 Options The following command line options are recognized by ocamlopt a Build a library cmxa a file with the object files cmx o files given on the command line instead of linking them into an executable file The name of the library can be set with the o option The default name is library cmxa If cclib or ccopt options are passed on the command line these options are stored in the resulting cmxa library Then linking with this library automatically adds back the cclib and ccopt options as if they had been provided on the command line unless the noautolink option is given Compile only Suppress the linking phase of the compilation Source code files are turned into compiled files but no executable file is produced This option is useful to compile modules separately cc ccomp Use ccomp as the C linker called to build the final executable and as the C compiler for compiling c source files cclib llibname Pass the Llibname option to the linker This causes the given C library to be linked with the program Chapter 11 Native code compilation ocamlopt 169 ccopt option Pass the given option to the C compiler and linker For instance ccopt Ldir causes the C linker to search for C libraries in directory dir compact Optimize the produced code for space rather than for time This results in slightly smaller but slight
114. longest first token Chapter 6 The Objective Caml language 95 Line number directives linenum directive 0 9 0 9 string character Preprocessors that generate Caml source code can insert line number directives in their output so that error messages produced by the compiler contain line numbers and file names referring to the source file before preprocessing instead of after preprocessing A line number directive is composed of a sharp sign followed by a positive integer the source line number optionally followed by a character string the source file name Line number directives are treated as blank characters during lexical analysis 6 2 Values This section describes the kinds of values that are manipulated by Objective Caml programs 6 2 1 Base values Integer numbers Integer values are integer numbers from 2 to 22 1 that is 1073741824 to 1073741823 The implementation may support a wider range of integer values on 64 bit platforms the current implementation supports integers ranging from 2 to 2 1 Floating point numbers Floating point values are numbers in floating point representation The current implementation uses double precision floating point numbers conforming to the IEEE 754 standard with 53 bits of mantissa and an exponent ranging from 1022 to 1023 Characters Character values are represented as 8 bit integers between 0 and 255 Character codes between 0
115. marshaled value Both Marshal data_size 20 19 and Marshal total_size 20 19 raise Failure if buff ofs does not contain a valid header To read the byte representation of a marshaled value into a string buffer the program needs to read first Marshal header_size 20 19 characters into the buffer then determine the length of the remainder of the representation using Marshal data_size 20 19 make sure the buffer is large enough to hold the remaining data then read it and finally call Marshal from_string 20 19 to unmarshal the value val data_size string gt int gt int See Marshal header_size 20 19 val total_size string gt int gt int See Marshal header_size 20 19 20 20 Module Nativeint Processor native integers This module provides operations on the type nativeint of signed 32 bit integers on 32 bit plat forms or signed 64 bit integers on 64 bit platforms This integer type has exactly the same width as that of a long integer type in the C compiler All arithmetic operations over nativeint are taken modulo 282 or 264 depending on the word size of the architecture 338 Performance notice values of type nativeint occupy more memory space than values of type int and arithmetic operations on nativeint are generally slower than those on int Use nativeint only when the application requires the extra bit of precision over the int type val zero nativeint The native integer 0 val one native
116. material in the pretty printer queue val get_formatter_tag_functions unit gt formatter_tag_functions Return the current tag functions of the pretty printer Changing the meaning of pretty printing indentation line breaking and print ing material val set_all_formatter_output_functions out string gt int gt int gt unit gt flush unit gt unit gt newline unit gt unit gt spaces int gt unit gt unit set_all_formatter_output_functions out flush outnewline outspace redirects the pretty printer output to the functions out and flush as described in set_formatter_output_functions In addition the pretty printer function that outputs a newline is set to the function outnewline and the function that outputs indentation spaces is set to the function outspace This way you can change the meaning of indentation which can be something else than just printing space characters and the meaning of new lines opening which can be connected to any other action needed by the application at hand The two functions outspace and outnewline are normally connected to out and flush respective default values for outspace and outnewline are out String make n O nand out n O 1 val get_all_formatter_output_functions unit gt string gt int gt int gt unit unit gt unit unit gt unit int gt unit Return the current output functions of the pretty printer including line br
117. mode and file permissions Pervasives open_in and Pervasives open_in_bin are special cases of this function input_char in_channel gt char Read one character from the given input channel Raise End_of_file if there are no more characters to read input_line in_channel gt string Read characters from the given input channel until a newline character is encountered Return the string of all characters read without the newline character at the end Raise End_of_file if the end of the file is reached at the beginning of line input in_channel gt string gt int gt int gt int input ic buf pos len reads up to len characters from the given channel ic storing them in string buf starting at character number pos It returns the actual number of characters read between 0 and len inclusive A return value of 0 means that the end of file was reached A return value between 0 and len exclusive means that not all requested len characters were read either because no more characters were available at that time or because the implementation found it convenient to do a partial read input must be called again to read the remaining characters if desired See also Pervasives really_input 19 2 for reading exactly len characters Exception Invalid_argument input is raised if pos and len do not designate a valid substring of buf val really_input in_channel gt string gt int gt int gt unit val val really_input
118. money2 k repr instead of lt repr k repr gt would not behave well with inheritance in a subclass money3 of money2 the times method would return an object of class money2 but not of class money3 as would be expected The class money could naturally carry another binary method Here is a direct definition class money x object self a val repr x method value repr method times k lt repr k x gt method leq p a repr lt p value method plus p a lt repr x p value gt end class money float gt object a val repr float method leq a gt bool method plus a gt a method print unit method times float gt a method value float end method print print_float repr 60 3 17 Friends The above class money reveals a problem that often occurs with binary methods In order to interact with other objects of the same class the representation of money objects must be revealed using a method such as value If we remove all binary methods here plus and leq the representation can easily be hidden inside objects by removing the method value as well However this is not possible as long as some binary requires access to the representation on object of the same class but different from self class safe_money x object self a val repr x method print print_float repr method times k lt repr
119. n are printed as ellipsis print_length n Limit the number of value nodes printed to at most n Remaining parts of values are printed as ellipsis 9 3 The toplevel and the module system Toplevel phrases can refer to identifiers defined in compilation units with the same mechanisms as for separately compiled units either by using qualified names Modulename localname or by using the open construct and unqualified names see section 6 3 However before referencing another compilation unit an implementation of that unit must be present in memory At start up the toplevel system contains implementations for all the modules in the the standard library Implementations for user modules can be entered with the load directive described above Referencing a unit for which no implementation has been provided results in the error Reference to undefined global Note that entering open Mod merely accesses the compiled interface cmi file for Mod but does not load the implementation of Mod and does not cause any error if no implementation of Mod has been loaded The error reference to undefined global Mod will occur only when executing a value or module definition that refers to Mod 9 4 Common errors This section describes and explains the most frequently encountered error messages 158 Cannot find file filename The named file could not be found in the current directory nor in the directories of the s
120. never be considered as totally applied ListLabels fold_left 0 1 2 3 This expression has type int gt int gt int but is here used with type a list When a function is passed as an argument to an higher order function labels must match in both types Neither adding nor removing labels are allowed This correspond to the commuting label mode of Objective Caml 3 00 through 3 02 with some additional flexi bility on total applications The so called classic mode nolabels options is now deprecated for normal use Chapter 4 Labels and variants 65 let h g g x 3 y 2 val h x int gt y int gt a gt a lt fun gt h f int 1 h This expression has type int gt int gt int but is here used with type x int gt y int gt a 4 1 1 Optional arguments An interesting feature of labeled arguments is that they can be made optional For optional parameters the question mark replaces the tilde of non optional ones and the label is also prefixed by in the function type Default values may be given for such optional parameters let bump step 1 x x step val bump step int gt int gt int lt fun gt bump 2 int 3 bump step 3 2 int 5 A function taking some optional arguments must also take at least one non labeled argument This is because the criterion for deciding whether an optional has been omitted is the application
121. not transmitted along the value of the data making it impossible to check that the data read back possesses the type expected by the context In particular the result type of the Marshal from_ functions is given as a but this is misleading the returned Caml value does not possess type a for all a it has one unique type which cannot be determined at compile type The programmer should explicitly give the expected type of the returned value using the following syntax 336 e Marshal from_channel chan type Anything can happen at run time if the object in the file does not belong to the given type The representation of marshaled values is not human readable and uses bytes that are not printable characters Therefore input and output channels used in conjunction with Marshal to_channel and Marshal from_channel must be opened in binary mode using e g open_out_bin or open_in_bin channels opened in text mode will cause unmarshaling errors on platforms where text channels behave differently than binary channels e g Windows type extern_flags No_sharing Don t preserve sharing Closures Send function closures The flags to the Marshal to_ functions below val to_channel Pervasives out_channel gt a gt extern_flags list gt unit Marshal to_channel chan v flags writes the representation of v on channel chan The flags argument is a possibly empty list of flags that governs the marshaling behavior wi
122. obj else lookup_obj obj 1 val lookup_obj lt gt gt lt gt as a list gt a lt fun gt let lookup_c obj lookup_obj obj all_c val lookup_c lt gt gt lt m int gt lt fun gt The type lt m int gt we see here is just the expansion of c due to the use of a reference we have succeeded in getting back an object of type c The previous coercion problem can often be avoided by first defining the abbreviation using a class type Chapter 3 Objects in Caml 53 class type c object method m int end class type c object method m int end class c c object method m 1 end and d object self inherit c method n 2 method as_c self gt c end class c c and d object method as_c c method m int method n int end It is also possible to use a virtual class Inheriting from this class simultaneously allows to enforce all methods of c to have the same type as the methods of c class virtual c object method virtual m int end class virtual c object method virtual m int end class c object self inherit c method m 1 end class c object method m int end One could think of defining the type abbreviation directly type c lt m int gt However the abbreviation c cannot be defined directly in a similar way It can only be defined by a class or a class type definition This is becaus
123. of Objective Caml phrases and executed as per the use directive described in section The evaluation outcode for each phrase are not displayed If the current directory does not contain an ocamlinit file but the user s home directory environment variable HOME does the latter is read and executed as described below The toplevel system does not perform line editing but it can easily be used in conjunc tion with an external line editor such as ledit ocaml2 or rlwrap see the Caml Hump http caml inria fr humps index_framed_caml html Another option is to use ocaml under Gnu Emacs which gives the full editing power of Emacs command run caml1 from library inf cam1 At any point the parsing compilation or evaluation of the current phrase can be interrupted by pressing ctr1 C or more precisely by sending the INTR signal to the ocaml process The toplevel then immediately returns to the prompt If scriptfile is given on the command line to ocaml the toplevel system enters script mode the contents of the file are read as a sequence of Objective Caml phrases and executed as per the use directive section 9 2 The outcome of the evaluation is not printed On reaching the end of file the ocaml command exits immediately No commands are read from standard input Sys argv is transformed ignoring all Objective Caml parameters and starting with the script file name in Sys argv 0 In script mode the first line of the script is
124. of a block as in Field v n w is safe only if v is a block newly allocated by alloc_small that is if no allocation took place between the allocation of v and the assignment to the field In all other cases never assign directly If the block has just been allocated by alloc_shr use initialize to assign a value to a field for the first time initialize kField v n w Otherwise you are updating a field that previously contained a well formed value then call the modify function modify amp Field v n w To illustrate the rules above here is a C function that builds and returns a list containing the two integers given as parameters First we write it using the simplified allocation functions value alloc_list_int int i1 int i2 CAMLparamO CAMLlocal2 result r r alloc 2 0 Allocate a cons cell Store_field r 0 Val_int i2 car the integer i2 Store_field r 1 Val_int 0 cdr the empty list result alloc 2 0 Allocate the other cons cell Store_field result 0 Val_int il car the integer i1 Store_field result 1 r cdr the first cons cell CAMLreturn result Here the registering of result is not strictly needed because no allocation takes place after it gets its value but it s easier and safer to simply register all the local variables that have type value Here is the same function written using the low level allocation functions We n
125. of q s elements The queue remains unchanged transfer at gt at gt unit transfer qi q2 adds all of q1 s elements at the end of the queue q2 then clears q1 It is equivalent to the sequence iter fun x gt add x q2 qi clear qi but runs in constant time 346 20 26 Module Random Pseudo random number generators PRNG Basic functions val init int gt unit Initialize the generator using the argument as a seed The same seed will always yield the same sequence of numbers val full_init int array gt unit Same as Random init 20 26 but takes more data as seed val self_init unit gt unit Initialize the generator with a more or less random seed chosen in a system dependent way val bits unit gt int Return 30 random bits in a nonnegative integer val int int gt int Random int bound returns a random integer between 0 inclusive and bound exclusive bound must be more than 0 and less than 227 val int32 Int32 t gt Int32 t Random int32 bound returns a random integer between 0 inclusive and bound exclusive bound must be greater than 0 val nativeint Nativeint t gt Nativeint t Random nativeint bound returns a random integer between 0 inclusive and bound exclusive bound must be greater than 0 val int64 Int64 t gt Int64 t Random int64 bound returns a random integer between 0 inclusive and bound exclusive bound must be greater than 0
126. of symbolic links EOVERFLOW File size or position not representable EUNKNOWNERR of int Unknown error 375 The type of error codes Errors defined in the POSIX standard and additional errors from UNIX98 and BSD All other errors are mapped to EUNKNOWNERR 376 exception Unix_error of error string string Raised by the system calls below when an error is encountered The first component is the error code the second component is the function name the third component is the string parameter to the function if it has one or the empty string otherwise val error_message error gt string Return a string describing the given error code val handle_unix_error a gt b gt a gt b handle_unix_error f x applies f to x and returns the result If the exception Unix_error is raised it prints a message describing the error and exits with code 2 Access to the process environment val environment unit gt string array Return the process environment as an array of strings with the format variable value val getenv string gt string Return the value associated to a variable in the process environment Raise Not_found if the variable is unbound This function is identical to Sys getenv val putenv string gt string gt unit Unix putenv name value sets the value associated to a variable in the process environment name is the name of the environment variable and value its new asso
127. of type Lazy t that encapsulates the computation of expr The argument expr is not evaluated at this point in the program Instead its evaluation will be performed the first time Lazy force is applied to the value v returning the actual value of expr Subsequent applications of Lazy force to v do not evaluate expr again For more information see the description of module Lazy in the standard library see section 20 15 7 7 Local modules The expression let module module name module expr in expr locally binds the module expres sion module expr to the identifier module name during the evaluation of the expression expr It then returns the value of expr For example let remove_duplicates comparison_fun string_list let module StringSet Set Make struct type t string let compare comparison_fun end in StringSet elements List fold_right StringSet add string_list StringSet empty 7 8 Private types type representation private constr decl constr decl private field decl field decl 138 Private types are variant or record types Values of these types can be de structured normally in pattern matching or via the expr field notation for record accesses However values of these types cannot be constructed directly by constructor application or record construction Moreover assignment on a mutable field of a private record type is not allowed The typical use of private types is in the export signature of a
128. one may wonder why they were added to core language variants rather than replacing them The answer is two fold One first aspect is that while being pretty efficient the lack of static type information allows for less optimizations and makes polymorphic variants slightly heavier than core language ones However noticeable differences would only appear on huge data structures More important is the fact that polymorphic variants while being type safe result in a weaker type discipline That is core language variants do actually much more than ensuring type safety 72 they also check that you use only declared constructors that all constructors present in a data structure are compatible and they enforce typing constraints to their parameters For this reason you must be more careful about making types explicit when you use polymorphic variants When you write a library this is easy since you can describe exact types in interfaces but for simple programs you are probably better off with core language variants Beware also that certain idioms make trivial errors very hard to find For instance the following code is probably wrong but the compiler has no way to see it type abc A B C type abc A BI CJ let f function As gt au abc gt other val f K A As B C gt string lt fun gt let f abc gt string f val f abc gt string lt
129. opened directories val opendir string gt dir_handle Open a descriptor on a directory val readdir dir_handle gt string Return the next entry in a directory Raises End_of_file when the end of the directory has been reached val rewinddir dir_handle gt unit Reposition the descriptor to the beginning of the directory val closedir dir_handle gt unit Close a directory descriptor Pipes and redirections val pipe unit gt file_descr file_descr 385 Create a pipe The first component of the result is opened for reading that s the exit to the pipe The second component is opened for writing that s the entrance to the pipe val mkfifo string gt file_perm gt unit Create a named pipe with the given permissions 386 High level process and redirection management val create_process string gt string array gt file_descr gt file_descr gt file_descr gt int create_process prog args new_stdin new_stdout new_stderr forks a new process that executes the program in file prog with arguments args The pid of the new process is returned immediately the new process executes concurrently with the current process The standard input and outputs of the new process are connected to the descriptors new_stdin new_stdout and new_stderr Passing e g stdout for new_stdout prevents the redirection and causes the new process to have the same standard output as the current process The exe
130. output channel to the input of the command val open_process_full string gt string array gt Pervasives in_channel Pervasives out_channel Pervasives in_channel Chapter 21 The unix library Unix system calls 387 Similar to Unix open_process 21 1 but the second argument specifies the environment passed to the command The result is a triple of channels connected respectively to the standard output standard input and standard error of the command val close_process_in Pervasives in_channel gt process_status Close channels opened by Unix open_process_in 21 1 wait for the associated command to terminate and return its termination status val close_process_out Pervasives out_channel gt process_status Close channels opened by Unix open_process_out 21 1 wait for the associated command to terminate and return its termination status val close_process Pervasives in_channel Pervasives out_channel gt process_status Close channels opened by Unix open_process 21 1 wait for the associated command to terminate and return its termination status val close_process_full Pervasives in_channel Pervasives out_channel Pervasives in_channel gt process_status Close channels opened by Unix open_process_ful1 21 1 wait for the associated command to terminate and return its termination status Symbolic links val symlink string gt string gt unit symlink source dest creates the file dest as a sym
131. p p set_x val set_x lt set_x a gt gt a lt fun gt let incr p set_x p get_succ_x p val incr lt get_x int set_x int gt a gt gt a lt fun gt 3 9 Multiple inheritance Multiple inheritance is allowed Only the last definition of a method is kept the redefinition in a subclass of a method that was visible in the parent class overrides the definition in the parent class Previous definitions of a method can be reused by binding the related ancestor Below super is bound to the ancestor printable_point The name super is a pseudo value identifier that can only be used to invoke a super class method as in super print class printable_colored_point y c object self val c c method color c inherit printable_point y as super method print print_string super print print_string print_string self color print_string end class printable_colored_point int gt string gt object val c string val mutable x int method color string method get_x int method move int gt unit method print unit end let p new printable_colored_point 17 red new point at 10 red val p printable_colored_point lt obj gt p print 10 red unit 44 A private method that has been hidden in the parent class is no longer visible and is thus not overridden Since initializers are treated as privat
132. p system interface 20 1 Module Arg Parsing of command line arguments This module provides a general mechanism for extracting options and arguments from the command line to the program Syntax of command lines A keyword is a character string starting with a An option is a keyword alone or followed by an argument The types of keywords are Unit Bool Set Clear String Set_string Int Set_int Float Set_float Tuple Symbol and Rest Unit Set and Clear keywords take no argument A Rest keyword takes the remaining of the command line as arguments Every other keyword takes the following word on the command line as argument Arguments not preceded by a keyword are called anonymous arguments Examples cmd is assumed to be the command name cmd flag a unit option cmd int 1 an int option with argument 1 cmd string foobar a string option with argument foobar cmd float 12 34 a float option with argument 12 34 cmd a b c three anonymous arguments a b and c cmd a b c d two anonymous arguments and a rest option with two arguments type spec Unit of unit gt unit Call the function with unit argument Bool of bool gt unit Call the function with a bool argument Set of bool Pervasives ref Set the reference to true Clear of bool Pervasives ref Set the reference to false String of string gt unit Call the function with a string argument 288 type type type ty
133. path that does not contain an object or variant type constructor are rejected except when the rectypes mode is selected If gt ident denotes an explicit polymorphic variable and typexpr denotes either an object or variant type the row variable of typexpr is captured by ident and quantified upon Chapter 6 The Objective Caml language 101 Variant types variant type tag spec tag spec gt tag spec tag spec lt tag spec full tag spec full gt tag name tag spec tag name of typexpr typexpr tag spec full tag name of typexpr amp typexpr typexpr Variant types describe the values a polymorphic variant may take The first case is an exact variant type all possible tags are known with their associated types and they can all be present Its structure is fully known The second case is an open variant type describing a polymorphic variant value it gives the list of all tags the value could take with their associated types This type is still compatible with a variant type containing more tags A special case is the unknown type which does not define any tag and is compatible with any variant type The third case is a closed variant type It gives information about all the possible tags and their associated types and which tags are known to potentially appear in values The above exact variant type is just an abbreviation for a closed variant type where al
134. pattern respectively This pattern behaves like pattern pattern 1 Polymorphic variant patterns The pattern tag name pattern matches all polymorphic variants whose tag is equal to tag name and whose argument matches pattern Variant abbreviation patterns If the type a b typeconstr tag t tag tn is defined then the pattern typeconstr is a shorthand for the or pattern tag _ t1 tag _ tn It matches 1 n all values of type typeconstr Tuple patterns The pattern pattern pattern matches n tuples whose components match the patterns pattern through pattern That is the pattern matches the tuple values v1 Vn such that pattern matches v fori 1 n Chapter 6 The Objective Caml language 105 Record patterns The pattern field pattern field pattern matches records that define at least the fields field through field and such that the value associated to field matches the pattern pattern for i 1 n The record value can define more fields than field field the values associated to these extra fields are not taken into account for matching Array patterns The pattern pattern pattern matches arrays of length n such that the i th array element matches the pattern pattern for i 1 n 106 Chapter 6 The Objective Caml language 107 6 7 Expressions expr argument value path
135. pointer is returned For example here is a C wrapper that calls the Caml function f above void call_caml_f int arg callback caml_named_value test function Val_int arg Chapter 18 Interfacing C with Objective Caml 251 The pointer returned by caml_named_value is constant and can safely be cached in a C variable to avoid repeated name lookups On the other hand the value pointed to can change during garbage collection and must always be recomputed at the point of use Here is a more efficient variant of call_caml_f above that calls caml_named_value only once void call_caml_f int arg static value closure_f NULL if closure_f NULL First time around look up by name closure_f caml_named_value test function callback closure_f Val_int arg 18 7 3 Registering Caml exceptions for use in C functions The registration mechanism described above can also be used to communicate excep tion identifiers from Caml to C The Caml code registers the exception by evaluating Callback register_exception n ezn where n is an arbitrary name and ern is an exception value of the exception to register For example exception Error of string let _ Callback register_exception test exception Error any string The C code can then recover the exception identifier using caml_named_value and pass it as first argument to the functions raise_constant raise_with_arg and raise_with_string described in section 1
136. process_status wait_pid p suspends the execution of the calling thread until the process specified by the process identifier p terminates Returns the pid of the child caught and its termination status as per Unix wait This function is not implemented under MacOS val wait_signal int list gt int wait_signal sigs suspends the execution of the calling thread until the process receives one of the signals specified in the list sigs It then returns the number of the signal received Signal handlers attached to the signals in sigs will not be invoked Do not call wait_signal concurrently from several threads on the same signals val yield unit gt unit Re schedule the calling thread without suspending it This function can be used to give scheduling hints telling the scheduler that now is a good time to switch to other threads 24 2 Module Mutex Locks for mutual exclusion Mutexes mutual exclusion locks are used to implement critical sections and protect shared mu table data structures against concurrent accesses The typical use is if m is the mutex associated with the data structure D 424 Mutex lock m Critical section that operates over D Mutex unlock m type t The type of mutexes val create unit gt t Return a new mutex val lock t gt unit Lock the given mutex Only one thread can have the mutex locked at any time A thread that attempts to lock a mutex already locked by another thread will susp
137. regular Caml symbols except that they cannot end with single quote 12 4 4 Error handling Error recovery is supported as follows when the parser reaches an error state no grammar rules can apply it calls a function named parse_error with the string syntax error as argument The default parse_error function does nothing and returns thus initiating error recovery see below The user can define a customized parse_error function in the header section of the grammar file The parser also enters error recovery mode if one of the grammar actions raises the Parsing Parse_error exception In error recovery mode the parser discards states from the stack until it reaches a place where the error token can be shifted It then discards tokens from the input until it finds three suc cessive tokens that can be accepted and starts processing with the first of these If no state can be uncovered where the error token can be shifted then the parser aborts by raising the Parsing Parse_error exception Refer to documentation on yacc for more details and guidance in how to use error recovery 12 5 Options The ocamlyacc command recognizes the following options v Generate a description of the parsing tables and a report on conflicts resulting from ambigu ities in the grammar The description is put in file grammar output bprefix Name the output files prefix ml prefix mli prefix output instead of the default naming convention Chap
138. representation of another object of the same class This is another instance of friend functions as seen in section Indeed this is the same mechanism used in the module Set in the absence of objects In the object oriented version of sets we only need to add an additional method tag to return the representation of a set Since sets are parametric in the type of elements the method tag has a parametric type a tag concrete within the module definition but abstract in its signature From outside it will then be guaranteed that two objects with a method tag of the same type will share the same representation module type SET sig type a tag class a c object b method is_empty bool method mem a gt bool method add a gt b method union b gt b method iter a gt unit gt unit method tag a tag end end module Set SET struct let rec merge 11 12 match 11 with gt 12 hi t1 gt match 12 with gt 11 h2 t2 gt if hi lt h2 then hi merge t1 12 else if hi gt h2 then h2 merge 11 t2 else merge t1 12 type a tag a list class a c object _ b val repr a list method is_empty repr method mem x List exists x repr method add x lt repr merge x repr gt method union s b lt repr merge repr s tag gt method iter f a gt unit List iter f repr HE HHH HH HH HH
139. same name as the ML function External functions thus defined can be specified in interface files or sig end signatures either as regular values val name type thus hiding their implementation as a C function or explicitly as manifest external functions external name type C function name The latter is slightly more efficient as it allows clients of the module to call directly the C function instead of going through the corresponding Caml function The arity number of arguments of a primitive is automatically determined from its Caml type in the external declaration by counting the number of function arrows in the type For instance input above has arity 4 and the input C function is called with four arguments Similarly 231 232 external input2 in_channel string int int gt int input2 has arity 1 and the input2 C function receives one argument which is a quadruple of Caml values Type abbreviations are not expanded when determining the arity of a primitive For instance type int_endo int gt int external f int_endo gt int_endo f external g int gt int gt int gt int f f has arity 1 but g has arity 2 This allows a primitive to return a functional value as in the f example above just remember to name the functional return type in a type abbreviation 18 1 2 Implementing primitives User primitives with arity n lt 5 are implemented by C functions that take n arg
140. set of C functions that implement the primitive operations Some bytecode instructions are provided to call these C functions designated by their offset in a table of functions the table of primitives In the default mode the Caml linker produces bytecode for the standard runtime system with a standard set of primitives References to primitives that are not in this standard set result in the unavailable C primitive error Unless dynamic loading of C libraries is supported see section below In the custom runtime mode the Caml linker scans the object files and determines the set of required primitives Then it builds a suitable runtime system by calling the native code linker with e the table of the required primitives e a library that provides the bytecode interpreter the memory manager and the standard primitives e libraries and object code files o files mentioned on the command line for the Caml linker that provide implementations for the user s primitives This builds a runtime system with the required primitives The Caml linker generates bytecode for this custom runtime system The bytecode is appended to the end of the custom runtime system so that it will be automatically executed when the output file custom runtime bytecode is launched To link in custom runtime mode execute the ocamlc command with e the custom option e the names of the desired Caml object files cmo and cma file
141. sets sorted type comparison Less Equal Greater type comparison Less Equal Greater module type ORDERED_TYPE sig type t val compare t gt t gt comparison end module type ORDERED_TYPE sig type t val compare t gt t gt comparison end module Set functor Elt ORDERED_TYPE gt struct bo 00 type element Elt t type set element list let empty let rec add x s match s with 0 gt x hd tl gt match Elt compare x hd with Equal gt s x is already in s Less gt xe 8 x is smaller than all elements of s Greater gt hd add x tl let rec member x s match s with gt false hd tl gt match Elt compare x hd with Equal gt true x belongs to s Less gt false x is smaller than all elements of s Greater gt member x tl end module Set functor Elt ORDERED_TYPE gt sig type element Elt t type set element list val empty a list val add Elt t gt Elt t list gt Elt t list val member Elt t gt Elt t list gt bool end By applying the Set functor to a structure implementing an ordered type we obtain set operations for this type module OrderedString struct type t string let compare x y if x y then Equal else if x lt y then Less else Greater end module OrderedString sig type t string val comp
142. sig type element OrderedString t type set AbstractSet OrderedString set val empty set val add element gt set gt set val member element gt set gt bool end AbstractStringSet add gee AbstractStringSet empty AbstractStringSet set lt abstr gt In an attempt to write the type constraint above more elegantly one may wish to name the signature of the structure returned by the functor then use that signature in the constraint 30 module type SET sig type element type set val empty set val add element gt set gt set val member element gt set gt bool end module type SET sig type element type set val empty set val add element gt set gt set val member element gt set gt bool end module WrongSet Set functor Elt ORDERED_TYPE gt SET module WrongSet functor Elt ORDERED_TYPE gt SET module WrongStringSet WrongSet OrderedString module WrongStringSet sig type element WrongSet OrderedString element type set WrongSet OrderedString set val empty set val add element gt set gt set val member element gt set gt bool end WrongStringSet add gee WrongStringSet empty This expression has type string but is here used with type WrongStringSet element WrongSet OrderedString element The problem here is that SET specifies the type element abstractly so that the type equality betwee
143. special case if the function has a known arity all the arguments are unlabeled and their number matches the number of non optional parameters then labels are ignored and non optional parameters are matched in their definition order Optional arguments are defaulted In all cases but exact match of order and labels without optional parameters the function type should be known at the application point This can be ensured by adding a type constraint Principality of the derivation can be checked in the principal mode Function definition Two syntactic forms are provided to define functions The first form is introduced by the keyword function 110 function pattern gt expr pattern gt expr This expression evaluates to a functional value with one argument When this function is applied to a value v this value is matched against each pattern pattern to pattern If one of these matchings succeeds that is if the value v matches the pattern pattern for some 7 then the expression expr associated to the selected pattern is evaluated and its value becomes the value of the function application The evaluation of expr takes place in an environment enriched by the bindings performed during the matching If several patterns match the argument v the one that occurs first in the function definition is selected If none of the patterns matches the argument the exception Match_failure is raised The other form of function def
144. strings Double_val v returns the floating point number contained in value v with type double Double_field v n returns the nt element of the array of floating point numbers v a block tagged Double_array_tag Store_double_field v n d stores the double precision floating point number d in the nt element of the array of floating point numbers v Data_custom_val v returns a pointer to the data part of the custom block v This pointer has type void and must be cast to the type of the data contained in the custom block 242 Int32_val v returns the 32 bit integer contained in the int32 v Int64_val v returns the 64 bit integer contained in the int64 v Nativeint_val v returns the long integer contained in the nativeint v The expressions Field v n Byte v n and Byte_u v n are valid l values Hence they can be assigned to resulting in an in place modification of value v Assigning directly to Field v n must be done with care to avoid confusing the garbage collector see below 18 4 4 Allocating blocks Simple interface Atom t returns an atom zero sized block with tag t Zero sized blocks are preallocated outside of the heap It is incorrect to try and allocate a zero sized block using the functions below For instance Atom 0 represents the empty array alloc n t returns a fresh block of size n with tag t If tis less than No_scan_tag then the fields of the block are initialized with a valid value i
145. taken to be compiled object bytecode These files are linked together along with the object files obtained by compiling ml arguments if any and the Objective Caml standard library to produce a standalone executable program The order in which cmo and ml arguments are presented on the command line is relevant compilation units are initialized in that order at run time and it is a link time error to use a component of a unit before having initialized it Hence a given x cmo file must come before all cmo files that refer to the unit z 143 144 e Arguments ending in cma are taken to be libraries of object bytecode A library of object bytecode packs in a single file a set of object bytecode files cmo files Libraries are built with ocamlc a see the description of the a option below The object files contained in the library are linked as regular cmo files see above in the order specified when the cma file was built The only difference is that if an object file contained in a library is not referenced anywhere in the program then it is not linked in e Arguments ending in c are passed to the C compiler which generates a o object file This object file is linked with the program if the custom flag is set see the description of custom below e Arguments ending in o or a obj or lib under Windows are assumed to be C object files and libraries They are passed to the C linker when linking in custom mode see the de
146. the calling thread for d seconds The other program threads continue to run during this time val join t gt unit join th suspends the execution of the calling thread until the thread th has terminated val wait_read Unix file_descr gt unit See Thread wait_write Chapter 24 The threads library 423 val wait_write Unix file_descr gt unit This function does nothing in this implementation val wait_timed_read Unix file_descr gt float gt bool See Thread wait_timed_read val wait_timed_write Unix file_descr gt float gt bool Suspend the execution of the calling thread until at least one character is available for reading wait_read or one character can be written without blocking wait_write on the given Unix file descriptor Wait for at most the amount of time given as second argument in seconds Return true if the file descriptor is ready for input output and false if the timeout expired These functions return immediately true in the Win32 implementation val select Unix file_descr list gt Unix file_descr list gt Unix file_descr list gt float gt Unix file_descr list Unix file_descr list Unix file_descr list Suspend the execution of the calling thead until input output becomes possible on the given Unix file descriptors The arguments and results have the same meaning as for Unix select This function is not implemented yet under Win32 val wait_pid int gt int Unix
147. the difference of the two specified character sets 178 regexp Repetition Match the concatenation of zero or more strings that match regexp regexp Strict repetition Match the concatenation of one or more strings that match regexp regexp Option Match either the empty string or a string matching regexp regexp regexp Alternative Match any string that matches either regexp or regexp regexp regexps Concatenation Match the concatenation of two strings the first matching regexp the second matching regexps regexp Match the same strings as regexp ident Reference the regular expression bound to ident by an earlier let ident regexp definition regexp as ident Bind the substring matched by regexp to identifier ident Concerning the precedences of operators and have highest precedence followed by then concatenation then alternation then as 12 2 5 Actions The actions are arbitrary Caml expressions They are evaluated in a context where the identifiers defined by using the as construct are bound to subparts of the matched string Additionally lexbuf is bound to the current lexer buffer Some typical uses for lexbuf in conjunction with the operations on lexer buffers provided by the Lexing standard library module are listed below Lexing lexeme lexbuf Return the matched string Lexing lexeme_char lexbuf n Return the nt character in the matched string The first character
148. the given big array with the given value See Bigarray Genarray fill for more details val of_array Ca b Bigarray kind gt c Bigarray layout gt a array array array gt a b c t Build a three dimensional big array initialized from the given array of arrays of arrays val map_file Unix file_descr gt Ca b Bigarray kind gt c Bigarray layout gt bool gt int gt int gt int gt a b c t Memory mapping of a file as a three dimensional big array See Bigarray Genarray map_file for more details end Three dimensional arrays The Array3 structure provides operations similar to those of Bigarray Genarray 29 1 but specialized to the case of three dimensional arrays Coercions between generic big arrays and fixed dimension big arrays val genarray_of_arrayl a b c Arrayl t gt a b c Genarray t Return the generic big array corresponding to the given one dimensional big array val genarray_of_array2 a b c Array2 t gt a b c Genarray t Return the generic big array corresponding to the given two dimensional big array val genarray_of_array3 a b c Array3 t gt a b c Genarray t Return the generic big array corresponding to the given three dimensional big array val arrayl_of_genarray a b c Genarray t gt a b c Array1 t Return the one dimensional big array correspondi
149. the value value show variable Print the value of the debugger variable variable info subject Give information about the given subject For instance info breakpoints will print the list of all breakpoints 16 4 Executing a program 16 4 1 Events Events are interesting locations in the source code corresponding to the beginning or end of evaluation of interesting sub expressions Events are the unit of single stepping stepping goes to the next or previous event encountered in the program execution Also breakpoints can only be set at events Thus events play the role of line numbers in debuggers for conventional languages During program execution a counter is incremented at each event encountered The value of this counter is referred as the current time Thanks to reverse execution it is possible to jump back and forth to any time of the execution Here is where the debugger events written bowtie are located in the source code e Following a function application arg bowtie e On entrance to a function fun x y z gt bowtie e On each case of a pattern matching definition function match with construct try with construct function pati gt bowtie expr1 ies patN gt bowtie exprN e Between subexpressions of a sequence 218 expr1 bowtie expr2 bowtie bowtie exprN e In the two branches of a conditional expression if cond then bowtie expri else bowtie expr2 e At the begin
150. to_int nativeint gt int Convert the given native integer type nativeint to an integer type int The high order bit is lost during the conversion 340 val of_float float gt nativeint Convert the given floating point number to a native integer discarding the fractional part truncate towards 0 The result of the conversion is undefined if after truncation the number is outside the range Nativeint min_int 20 20 Nativeint max_int 20 20 val to_float nativeint gt float Convert the given native integer to a floating point number val of_int32 int32 gt nativeint Convert the given 32 bit integer type int32 to a native integer val to_int32 nativeint gt int32 Convert the given native integer to a 32 bit integer type int32 On 64 bit platforms the 64 bit native integer is taken modulo 2 i e the top 32 bits are lost On 32 bit platforms the conversion is exact val of_string string gt nativeint Convert the given string to a native integer The string is read in decimal by default or in hexadecimal octal or binary if the string begins with Ox Oo or Ob respectively Raise Failure int_of_string if the given string is not a valid representation of an integer or if the integer represented exceeds the range of integers representable in type nativeint val to_string nativeint gt string Return the string representation of its argument in decimal type t nativeint An a
151. totally ordered type 20 29 Module Sort Sorting and merging lists This module is obsolete and exists only for backward compatibility The sorting functions in Array 20 2 and List 20 17 should be used instead The new functions are faster and use less memory Sorting and merging lists val list a gt a gt bool gt a list gt a list Sort a list in increasing order according to an ordering predicate The predicate should return true if its first argument is less than or equal to its second argument val array a gt a gt bool gt a array gt unit Sort an array in increasing order according to an ordering predicate The predicate should return true if its first argument is less than or equal to its second argument The array is sorted in place val merge a gt a gt bool gt a list gt a list gt a list Merge two lists according to the given predicate Assuming the two argument lists are sorted according to the predicate merge returns a sorted list containing the elements from the two lists The behavior is undefined if the two argument lists were not sorted 20 30 Module Stack Last in first out stacks This module implements stacks LIFOs with in place modification type at The type of stacks containing elements of type a exception Empty 356 val val val val val val val val val Raised when Stack pop 20 30 or Stack top 20 3
152. type This constraint forces the type of expr to be compatible with type Parenthesized expressions can also contain coercions expr type gt type see subsec tion below Function application Function application is denoted by juxtaposition of possibly labeled expressions The expression expr argument argument evaluates the expression expr and those appearing in argument to argument The expression expr must evaluate to a functional value f which is then applied to the values of argument argument The order in which the expressions expr argument argument are evaluated is not spec ified Arguments and parameters are matched according to their respective labels Argument order is irrelevant except among arguments with the same label or no label If a parameter is specified as optional label prefixed by in the type of expr the corresponding argument will be automatically wrapped with the constructor Some except if the argument itself is also prefixed by in which case it is passed as is If a non labeled argument is passed and its corresponding parameter is preceded by one or several optional parameters then these parameters are defaulted i e the value None will be passed for them All other missing parameters without corresponding argument both optional and non optional will be kept and the result of the function will still be a function of these missing parameters to the body of f As a
153. type of strings val compare t gt t gt int The comparison function for strings with the same specification as Pervasives compare Along with the type t this function compare allows the module String to be passed as argument to the functors Set Make 20 28 and Map Make 20 18 364 20 34 Module Sys System interface val val val val val val val val val val val argv string array The command line arguments given to the process The first element is the command name used to invoke the program The following elements are the command line arguments given to the program executable_name string The name of the file containing the executable currently running file_exists string gt bool Test if a file with the given name exists remove string gt unit Remove the given file name from the file system rename string gt string gt unit Rename a file The first argument is the old name and the second is the new name If there is already another file under the new name rename may replace it or raise an exception depending on your operating system getenv string gt string Return the value associated to a variable in the process environment Raise Not_found if the variable is unbound command string gt int Execute the given shell command and return its exit code time unit gt float Return the processor time in seconds used by the program since t
154. type with the same name e Ina module there must not be two values two types or two exceptions with the same name Values defined in tuple as in let x y z 1 2 3 are not kept by OCamldoc Avoid the following construction open Foo which has a module Bar with a value x module Foo struct module Bar struct let x 1 end end let dummy Bar x In this case OCamldoc will associate Bar x to the x of module Foo defined just above instead of to the Bar x defined in the opened module Foo 15 2 Syntax of documentation comments Comments containing documentation material are called special comments and are written between and Special comments must start exactly with Comments beginning with and more than two are ignored 15 2 1 Placement of documentation comments OCamldoc can associate comments to some elements of the language encountered in the source files The association is made according to the locations of comments with respect to the language elements The locations of comments in mli and m1 files are different Comments in m1i files A special comment is associated to an element if it is placed before or after the element A special comment before an element is associated to this element if e There is no blank line or another special comment between the special comment and the ele ment However a regular comment can occur between the special comment and the element 202 e The spe
155. unit Array fill a ofs len x modifies the array a in place storing x in elements number ofs to ofs len 1 Raise Invalid_argument Array fill if ofs and len do not designate a valid subarray of a blit a array gt int gt a array gt int gt int gt unit Array blit v1 o1 v2 02 len copies len elements from array v1 starting at element number o1 to array v2 starting at element number o2 It works correctly even if v1 and v2 are the same array and the source and destination chunks overlap Raise Invalid_argument Array blit if o1 and len do not designate a valid subarray of vi or if o2 and len do not designate a valid subarray of v2 to_list a array gt a list Array to_list a returns the list of all the elements of a of_list a list gt a array Array of_list 1 returns a fresh array containing the elements of 1 iter a gt unit gt a array gt unit Array iter f a applies function f in turn to all the elements of a It is equivalent to f a 0O f a 1 f a Array length a 1 map Ca gt b gt a array gt b array Array map f a applies function f to all the elements of a and builds an array with the results returned by f f a 0 f a 1 f a Array length a 1 iteri int gt a gt unit gt a array gt unit 292 Same as Array iter but the function is applied to the index of the element as first argument
156. val signal t gt unit signal c restarts one of the processes waiting on the condition variable c val broadcast t gt unit broadcast c restarts all processes waiting on the condition variable c 24 4 Module Event First class synchronous communication This module implements synchronous inter thread communications over channels As in John Reppy s Concurrent ML system the communication events are first class values they can be built and combined independently before being offered for communication type a channel The type of communication channels carrying values of type a val new_channel unit gt a channel Return a new channel type a event The type of communication events returning a result of type a val send a channel gt a gt unit event send ch v returns the event consisting in sending the value v over the channel ch The result value of this event is val receive a channel gt a event receive ch returns the event consisting in receiving a value from the channel ch The result value of this event is the value received val always a gt a event always v returns an event that is always ready for synchronization The result value of this event is v val choose a event list gt a event 426 choose evl returns the event that is the alternative of all the events in the list evl val wrap a event gt a gt b gt
157. where the recursion goes through an object type are supported S Keep the assembly code produced during the compilation The assembly code for the source file z ml is saved in the file z s thread Compile or link multithreaded programs in combination with the system threads library described in chapter unsafe Turn bound checking off on array and string accesses the v i and s i constructs Programs compiled with unsafe are therefore faster but unsafe anything can happen if the program accesses an array or string outside of its bounds v Print the version number of the compiler and the location of the standard library directory then exit verbose Print all external commands before they are executed in particular invocations of the assem bler C compiler and linker version Print the version number of the compiler in short form e g 3 06 then exit 172 w warning list Enable or disable warnings according to the argument warning list The argument is a string of one or several characters with the following meaning for each character A a enable disable all warnings C c enable disable warnings for suspicious comments D d enable disable warnings for deprecated features F f enable disable warnings for partially applied functions i e f x expr where the appli cation f x has a function type L 1 enable disable warnings for labels omitted in application M m enable disable warnings for overriden met
158. with full imperative features This includes the usual while and for loops as well as mutable data structures such as arrays Arrays are either given in extension between and brackets or allocated and initialized with the Array create function then filled up later by assignments For instance the function below sums two vectors represented as float arrays componentwise let add_vect vi v2 let len min Array length vi Array length v2 in let res Array create len 0 0 in for i 0 to len 1 do res i lt vi i v2 i done res val add_vect float array gt float array gt float array lt fun gt add_vect 1 0 2 0 I 3 0 4 0 float array 4 6 1 Record fields can also be modified by assignment provided they are declared mutable in the definition of the record type type mutable_point mutable x float mutable y float type mutable_point mutable x float mutable y float let translate p dx dy p x lt p x dx p y lt p y dy val translate mutable_point gt float gt float gt unit lt fun gt let mypoint x 0 0 y 0 0 val mypoint mutable_point x 0 y 0 translate mypoint 1 0 2 0 unit mypoint mutable_point x 1 y 2 Caml has no built in notion of variable identifiers whose current value can be changed by assignment The let binding is not an assignme
159. 0 is applied to an empty stack create unit gt at Return a new stack initially empty push a gt a t gt unit push x s adds the element x at the top of stack s pop at gt a pop s removes and returns the topmost element in stack s or raises Empty if the stack is empty top at gt a top s returns the topmost element in stack s or raises Empty if the stack is empty clear a t gt unit Discard all elements from a stack copy at gt at Return a copy of the given stack is_empty a t gt bool Return true if the given stack is empty false otherwise length a t gt int Return the number of elements in a stack iter a gt unit gt a t gt unit iter f s applies f in turn to all elements of s from the element at the top of the stack to the element at the bottom of the stack The stack itself is unchanged 20 31 Module StdLabels Standard labeled libraries This meta module provides labelized version of the Array 20 2 List 20 17 and String 20 33 modules They only differ by their labels Detailed interfaces can be found in arrayLabels m1i listLabels mli and stringLabels mli module Array sig Chapter 20 The standard library val val val val val val val val val val val val val val 357 length a array gt int get a array gt int gt a set 7a array gt int gt a gt unit make int
160. 0 2 and Pervasives ref are guaranteed to be heap allocated and non constant except when the length argument is 0 val finalise_release unit gt unit A finalisation function may call finalise_release to tell the GC that it can launch the next finalisation function without waiting for the current one to return type alarm An alarm is a piece of data that calls a user function at the end of each major GC cycle The following functions are provided to create and delete alarms 316 val create_alarm unit gt unit gt alarm create_alarm f will arrange for f to be called at the end of each major GC cycle starting with the current cycle or the next one A value of type alarm is returned that you can use to call delete_alarm val delete_alarm alarm gt unit delete_alarm a will stop the calls to the function associated to a Calling delete_alarm a again has no effect 20 11 Module Genlex A generic lexical analyzer This module implements a simple standard lexical analyzer presented as a function from char acter streams to token streams It implements roughly the lexical conventions of Caml but is parameterized by the set of keywords of your language Example a lexer suitable for a desk calculator is obtained by let lexer make_lexer wou h nym Tet wy The associated parser would be a function from token stream to for instance int and would have rules such as let parse_e
161. 0 3 Finally step 3 execute the ocamlc command with e the names of the desired Caml object files cmo and cma files e the names of the C shared libraries so or d11 files that implement the required primitives Under Unix and Windows a library named dllname so respectively d11 residing in one of the standard library directories can also be specified as dllib lname Do not set the custom flag otherwise you re back to static linking as described in section 18 1 3 Under Unix the ocamlmklib tool see section 18 10 automates steps 2 and 3 As in the case of static linking it is possible and recommended to record the names of C libraries in a Caml cmo library archive Consider again a Caml library mylib cma built from the Caml object files a cmo and b cmo which reference C code in dllmylib so If the library is built as follows 236 ocamlc a o mylib cma a cmo b cmo dllib lmylib users of the library can simply link with mylib cma ocamlc o myprog mylib cma and the system will automatically add the dllib lmylib option achieving the same effect as ocamlc o myprog a cmo b cmo dllib lmylib Using this mechanism users of the library mylib cma do not need to known that it references C code nor whether this C code must be statically linked using custom or dynamically linked 18 1 5 Choosing between static linking and dynamic linking After having described two different ways of linking C code w
162. 1 lt fun gt let to_c2 x x gt c2 val to_c2 c2 gt c2 lt fun gt Note the difference between the two coercions in the second case the type c2 lt m a gt as a is polymorphically recursive according to the explicit recursion in the class type of c2 hence the success of applying this coercion to an object of class c0 On the other hand in the first case c1 was only expanded and unrolled twice to obtain lt m lt m cl gt gt remember co1 lt m cl gt without introducing recursion You may also note that the type of to_c2 is c2 gt c2 while the type of to_c1 is more general than c1 gt c1 This is not always true since there are class types for which some instances of c are not subtypes of c as explained in section 3 16 Yet for parameterless classes the coercion _ gt c is always more general than _ c gt c A common problem may occur when one tries to define a coercion to a class c while defining class c The problem is due to the type abbreviation not being completely defined yet and so its subtypes are not clearly known Then a coercion _ gt c or _ c gt c is taken to be the identity function as in 52 function x gt x gt a a gt a lt fun gt As a consequence if the coercion is applied to self as in the following example the type of self is unified with the closed type c a closed object type is an object typ
163. 10 s n format_result result return 0 To build the whole program just invoke the C compiler as follows cc o prog main c mod a lcurses On some machines you may need to put 1termcap or 1lcurses ltermcap instead of lcurses Chapter 18 Interfacing C with Objective Caml 255 18 9 Advanced topic custom blocks Blocks with tag Custom_tag contain both arbitrary user data and a pointer to a C struct with type struct custom_operations that associates user provided finalization comparison hashing serialization and deserialization functions to this block 18 9 1 The struct custom_operations The struct custom_operations is defined in lt cam1 custom h gt and contains the following fields e char identifier A zero terminated character string serving as an identifier for serialization and deserialization operations e void finalize value v The finalize field contains a pointer to a C function that is called when the block becomes unreachable and is about to be reclaimed The block is passed as first argument to the function The finalize field can also be NULL to indicate that no finalization function is associated with the block Important note the v parameter of this function is of type value but it must not be declared using the CAMLparam macros e int compare value v1 value v2 The compare field contains a pointer to a C function that is called whenever two custom blocks are compared using Caml s generic
164. 2 types The type class path is a special kind of abbreviation This abbreviation unifies with the type of any object belonging to a subclass of class class path It is handled in a special way as it usually hides a type variable an ellipsis representing the methods that may be added in a subclass In particular it vanishes when the ellipsis gets instantiated Each type expression class path defines a new type variable so type class path gt class path is usually not the same as type class path as ident gt ident Use of types to abbreviate variant types is deprecated If t is an exact variant type then t translates to lt t and t gt tag tag translates to lt t gt tag tag Variant and record types There are no type expressions describing defined variant types nor record types since those are always named i e defined before use and referred to by name Type definitions are described in section 6 8 1 6 5 Constants constant integer literal float literal char literal string literal constr false true O tag name The syntactic class of constants comprises literals from the four base types integers floating point numbers characters character strings and constant constructors from both normal and polymorphic variants as well as the special constants false true and which behave like constant constructors Chapter 6 The Objective Cam
165. 271 Return the absolute value of the argument val max_int int The greatest representable integer val min_int int The smallest representable integer Bitwise operations val land int gt int gt int Bitwise logical and val lor int gt int gt int Bitwise logical or val lxor int gt int gt int Bitwise logical exclusive or val lnot int gt int Bitwise logical negation val lsl int gt int gt int n 1sl m shifts n to the left by m bits The result is unspecified ifm lt 0 orm gt bitsize where bitsize is 32 on a 32 bit platform and 64 on a 64 bit platform val lsr int gt int gt int n lsr m shifts n to the right by m bits This is a logical shift zeroes are inserted regardless of the sign of n The result is unspecified ifm lt 0 or m gt bitsize val asr int gt int gt int n asr m shifts n to the right by m bits This is an arithmetic shift the sign bit of n is replicated The result is unspecified ifm lt 0 or m gt bitsize Floating point arithmetic Caml s floating point numbers follow the IEEE 754 standard using double precision 64 bits numbers Floating point operations never raise an exception on overflow underflow division by zero etc Instead special IEEE numbers are returned as appropriate such as infinity for 1 0 0 0 neg_infinity for 1 0 0 0 and nan not a number for 0 0 0 0 These special numbers then propagate t
166. 5 exception Sys_blocked_io A special case of Sys_error raised when no I O is possible on a non blocking I O channel exception Undefined_recursive_module of string int int Exception raised when an ill founded recursive module definition is evaluated See section 7 9 The arguments are the location of the definition in the source code file name line number column number 268 19 2 Module Pervasives The initially opened module This module provides the basic operations over the built in types numbers booleans strings exceptions references lists arrays input output channels This module is automatically opened at the beginning of each compilation All components of this module can therefore be referred by their short name without prefixing them by Pervasives Exceptions val raise exn gt a Raise the given exception value val invalid_arg string gt a Raise exception Invalid_argument with the given string val failwith string gt a Raise exception Failure with the given string exception Exit The Exit exception is not raised by any library function It is provided for use in your programs Comparisons val a gt a gt bool e1 e2 tests for structural equality of e1 and e2 Mutable structures e g references and arrays are equal if and only if their current contents are structurally equal even if the two mutable objects are not the same physical obj
167. 5 326 833 34 10 517 B52 B53 B59 50 363 367 369 422 424 439 459 463 tag 304 take 345 tan 272 tanh 273 tcdrain 404 tcflow 404 tcflush 404 tcgetattr tcsendbreak 404 tcsetattr 404 temp_file 299 terminal _io 403 text_size 434 Thread ThreadUnix time timed_read timed_write times 487 Tk a8 EBT tm 890 to_buffer 336 to_channel to_float to_hex to_int to_int32 to_list to_nativeint 325 vo_string B22 B23 B39 E10 B token 316 top B15 550 total_size transfer transp truncate try_lock umask uncapitalize Undef ined 326 Undefined_recursive_module union 353 unit unit_big_int units Unix Unix_error UnixLabels module unlink 383 unlock unsafe_blit 359 unsafe_fill unsafe_get unsafe_set update uppercase usage 289 usage_msg 288 utimes vait B7 E25 EZ wait_flag wait_next_event 488 wait_pid 423 wait_read wait_signal 423 wait_timed_read wait_timed_write wait_write waitpid Weak white word_size 365 wrap wrap_abort 426 write yellow yield zero_big_int INDEX OF KEYWORDS Index of keywords and see let type class 121 124 125 as D0 0 03 0 2 75 assert 137 begin 07 09 class 429 23 50 1 constraint 119 121 124 do see while for done see while for downto see for
168. 8 float list 2 718 3 14 The sort function above does not modify its input list it builds and returns a new list con taining the same elements as the input list in ascending order There is actually no way in Caml to modify in place a list once it is built we say that lists are immutable data structures Most Caml data structures are immutable but a few most notably arrays are mutable meaning that they can be modified in place at any time 1 3 Functions as values Caml is a functional language functions in the full mathematical sense are supported and can be passed around freely just as any other piece of data For instance here is a deriv function that takes any float function as argument and returns an approximation of its derivative function let deriv f dx function x gt f x dx f x dx val deriv float gt float gt float gt float gt float lt fun gt let sin deriv sin te 6 val sin float gt float lt fun gt sin pi float 1 00000000013961143 Even function composition is definable let compose f g function x gt f g x val compose a gt b gt c gt a gt c gt b lt fun gt let cos2 compose square cos val cos2 float gt float lt fun gt Functions that take other functions as arguments are called functionals or higher order functions Functionals are especially useful to provi
169. 8 4 5 to actually raise the exception For example here is a C function that raises the Error exception with the given argument void raise_error char msg raise_with_string caml_named_value test exception msg 18 7 4 Main program in C In normal operation a mixed Caml C program starts by executing the Caml initialization code which then may proceed to call C functions We say that the main program is the Caml code In some applications it is desirable that the C code plays the role of the main program calling Caml functions when needed This can be achieved as follows e The C part of the program must provide a main function which will override the default main function provided by the Caml runtime system Execution will start in the user defined main function just like for a regular C program e At some point the C code must call caml_main argv to initialize the Caml code The argv argument is a C array of strings type char terminated with a NULL pointer which 252 represents the command line arguments as passed as second argument to main The Caml array Sys argv will be initialized from this parameter For the bytecode compiler argv 0 and argv 1 are also consulted to find the file containing the bytecode e The call to caml_main initializes the Caml runtime system loads the bytecode in the case of the bytecode compiler and executes the initialization code of the Caml program Typically this initiali
170. AY_KIND_MASK kind of array elements The kind of array elements is one of the following constants Constant Element kind BIGARRAY_FLOAT32 32 bit single precision floats BIGARRAY_FLOAT64 64 bit double precision floats BIGARRAY_SINT8 8 bit signed integers BIGARRAY_UINT8 8 bit unsigned integers BIGARRAY_SINT16 16 bit signed integers BIGARRAY_UINT16 16 bit unsigned integers BIGARRAY_INT32 32 bit signed integers BIGARRAY_INT64 64 bit signed integers BIGARRAY_CAML_INT 31 or 63 bit signed integers BIGARRAY_NATIVE_INT 32 or 64 bit platform native integers The following example shows the passing of a two dimensional big array to a C function and a Fortran function extern void my_c_function double data int dimx int dimy extern void my_fortran_function_ double data int dimx int dimy value caml_stub value bigarray int dimx Bigarray_val bigarray gt dim 0 int dimy Bigarray_val bigarray gt dim 1 C passes scalar parameters by value my_c_function Data_bigarray_val bigarray dimx dimy Fortran passes all parameters by reference my_fortran_function_ Data_bigarray_val bigarray amp dimx amp dimy return Val_unit 29 2 3 Wrapping a C or Fortran array as a Caml big array A pointer p to an already allocated C or Fortran array can be wrapped and returned to Caml as a big array using the alloc_bigarray or alloc_bigarray_dims functions 472 e alloc_bigarray kind layout
171. C As explained in chapter 18 such code must be linked with C libraries that implement the required fC function If the C libraries in question are not shared libraries DLLs the code must be linked in custom runtime mode Fix add the required C libraries to the command line and possibly the custom option Chapter 9 The toplevel system ocaml This chapter describes the toplevel system for Objective Caml that permits interactive use of the Objective Caml system through a read eval print loop In this mode the system repeatedly reads Caml phrases from the input then typechecks compile and evaluate them then prints the inferred type and result value if any The system prints a sharp prompt before reading each phrase Input to the toplevel can span several lines It is terminated by a double semicolon The toplevel input consists in one or several toplevel phrases with the following syntax toplevel input toplevel phrase toplevel phrase definition expr ident directive argument definition let rec let binding and let binding external value name typexpr external declaration type definition exception definition module module name module type module expr module type modtype name module type open module path directive argument nothing string literal integer literal value path A phrase can consist of a definition similar to those found in implementations of compil
172. Caml versions Referring to named objects value path value name module path value name constr constr name module path constr name typeconstr typeconstr name extended module path typeconstr name field field name module path field name module path module name module path module name extended module path module name extended module path module name extended module path extended module path modtype path modtype name extended module path modtype name class path class name module path class name A named object can be referred to either by its name following the usual static scoping rules for names or by an access path prefix name where prefix designates a module and name is Chapter 6 The Objective Caml language 99 the name of an object defined in that module The first component of the path prefix is either a simple module name or an access path name name2 in case the defining module is itself nested inside other modules For referring to type constructors or module types the prefix can also contain simple functor applications as in the syntactic class extended module path above in case the defining module is the result of a functor application Label names tag names method names and instance variable names need not be qualified the former three are global labels while the latter are local to a class 6 4 Type expressions typexpr ident
173. Float 3 14159 number Float 126 14159 The most common usage of variant types is to describe recursive data structures Consider for example the type of binary trees type a btree Empty Node of a a btree a btree type a btree Empty Node of a a btree a btree This definition reads as follow a binary tree containing values of type a an arbitrary type is either empty or is a node containing one value of type a and two subtrees containing also values of type a that is two a btree Operations on binary trees are naturally expressed as recursive functions following the same structure as the type definition itself For instance here are functions performing lookup and insertion in ordered binary trees elements increase from left to right let rec member x btree match btree with Empty gt false Node y left right gt if x y then true else if x lt y then member x left else member x right val member a gt a btree gt bool lt fun gt let rec insert x btree match btree with Empty gt Node x Empty Empty Node y left right gt if x lt y then Node y insert x left right else Node y left insert x right val insert a gt a btree gt a btree lt fun gt 16 1 5 Imperative features Though all examples so far were written in purely applicative style Caml is also equipped
174. HH HHH HHH HHH HH HH HH HH HHH HH OH OF OH OH OH OF OF balance lt balance plus neg x self trace Retrieval x x This shows the use of modules to group several class definitions that can in fact be thought of as 78 a single unit This unit would be provided by a bank for both internal and external uses This is implemented as a functor that abstracts over the currency so that the same code can be used to provide accounts in different currencies The class bank is the real implementation of the bank account it could have been inlined This is the one that will be used for further extensions refinements etc Conversely the client will only be given the client view module Euro_account Account Euro module Client Euro_account Client Euro_account new Client account new Euro c 100 Hence the clients do not have direct access to the balance nor the history of their own accounts Their only way to change their balance is to deposit or withdraw money It is important to give the clients a class and not just the ability to create accounts such as the promotional discount account so that they can personalize their account For instance a client may refine the deposit and withdraw methods so as to do his own financial bookkeeping automatically On the other hand the function discount is given as such with no possibility for further personalization It is important that to provide the client s view as a f
175. Here is for instance a structure packaging together a type of priority queues and their operations module PrioQueue if lprio lt rprio then Node lprio lelt remove_top left right struct type priority int type a queue Empty Node of priority a a queue a queue let empty Empty let rec insert queue prio elt match queue with Empty gt Node prio elt Empty Empty Node p e left right gt if prio lt p then Node prio elt insert right p e left else Node p e insert right prio elt left exception Queue_is_empty let rec remove_top function Empty gt raise Queue_is_empty Node prio elt left Empty gt left Node prio elt Empty right gt right Node prio elt Node lprio lelt _ _ as left Node rprio relt _ _ as right gt 25 else Node rprio relt left remove_top right let extract function Empty gt raise Queue_is_empty Node prio elt _ _ as queue gt prio elt remove_top queue end module PrioQueue sig type priority int type a queue Empty Node of priority a a queue a queue val empty a queue val insert a queue gt priority gt a gt a queue exception Queue_is_empty val remove_top a queue gt a queue val extract a queue gt priority a a queue end Outside the structure its components can be re
176. In the ideal the right function name with right labels shall be enough to understand the function s meaning Since one can get this information with OCamlBrowser or the ocam1 toplevel the documentation is only used when a more detailed specification is needed Chapter 4 Labels and variants 69 4 2 Polymorphic variants Variants as presented in section are a powerful tool to build data structures and algorithms However they sometimes lack flexibility when used in modular programming This is due to the fact every constructor reserves a name to be used with a unique type On cannot use the same name in another type or consider a value of some type to belong to some other type with more constructors With polymorphic variants this original assumption is removed That is a variant tag does not belong to any type in particular the type system will just check that it is an admissible value according to its use You need not define a type before using a variant tag A variant type will be inferred independently for each of its uses Basic use In programs polymorphic variants work like usual ones You just have to prefix their names with a backquote character On Off gt Off On list On Off Number 1 gt Number of int Number 1 let f function On gt 1 Off gt O Number n gt n val f lt Number of int Off On gt int lt fun gt
177. It provides multiple threads of control also called lightweight processes that execute concurrently in the same memory space Threads communicate by in place modification of shared data structures or by sending and receiving data on communication channels The threads library is implemented by time sharing on a single processor It will not take advantage of multi processor machines Using this library will therefore never make programs run faster However many programs are easier to write when structured as several communicating processes Two implementations of the threads library are available depending on the capabilities of the operating system e System threads This implementation builds on the OS provided threads facilities POSIX 1003 1 threads for Unix and Win32 threads for Windows When available system threads support both bytecode and native code programs e VM level threads This implementation performs time sharing and context switching at the level of the OCaml virtual machine bytecode interpreter It is available on Unix systems and supports only bytecode programs It cannot be used with native code programs Programs that use system threads must be linked as follows ocamlc thread other options threads cma other files ocamlopt thread other options threads cmxa other files All object files on the command line must also have been compiled with the thread option see chapter 8 Programs that use VM level threa
178. MEO Timeout for input operations SO_SNDTIMEO Timeout for output operations The socket options that can be consulted with Unix getsockopt_float and modified with Unix setsockopt_float 21 1 These options have a floating point value representing a time in seconds The value 0 means infinite timeout val getsockopt file_descr gt socket_bool_option gt bool Return the current status of a boolean valued option in the given socket val setsockopt file_descr gt socket_bool_option gt bool gt unit Set or clear a boolean valued option in the given socket val getsockopt_int file_descr gt socket_int_option gt int Same as Unix getsockopt for an integer valued socket option val setsockopt_int file_descr gt socket_int_option gt int gt unit Same as Unix setsockopt for an integer valued socket option val getsockopt_optint file_descr gt socket_optint_option gt int option Same as Unix getsockopt for a socket option whose value is an int option 398 val setsockopt_optint file_descr gt socket_optint_option gt int option gt unit Same as Unix setsockopt for a socket option whose value is an int option val getsockopt_float file_descr gt socket_float_option gt float Same as Unix getsockopt for a socket option whose value is a floating point number val setsockopt_float file_descr gt socket_float_option gt float gt unit Same as Unix setsockopt for a socket opt
179. The Objective Caml system release 3 08 Documentation and user s manual Xavier Leroy with Damien Doligez Jacques Garrigue Didier R my and J r me Vouillon July 13 2004 Copyright 2004 Institut National de Recherche en Informatique et en Automatique Contents I An introduction to Objective Caml 9 1 PES BIC e a wy e a aes a ape on et aad E e Cy ae abe aa a a Get Pe ee an 11 a avi ee Bok Bee Beas ee eee eee ed ee ee ee a ee 12 1 3 Functions as values 2 a 13 14 Records and variants a ima aa a E E A i ke a i e A a a 14 1 5 Imperative features ooa a ee 16 1 6 Exceptions sa s ese aoa iok aow ik a da a d a a be e i atap de a ea eyes ee 18 1 7 Symbolic processing of expressions o oo o 19 1 8 Pretty printing and parsing o oo a a ee 20 a E E on a a Stes a a epee a eae 23 25 2 1 DUTMCEUEGSH hc lt 6 fe eye s Sec a oe oy Ga ch es tee Se teh Pe ee Gt Go Bo Sst ee ie ee aai 25 cae su ee Sy eee ee Bed ee he Bee ee ee ee et ee 26 2 3 HUNCEOIS o porie Hie we ea Be ORU ot amp ce ae Ge ee SS EN AS eee a amp iai 27 a ee eee nae a a eee 29 2 5 Modules and separate compilation 0 0 0002 eee ee eee 31 3 Objects in Caml 33 Ae Eo BS os Ge ee a oe 8 ee oe ee es 33 Ss wos Beh SS tee dh ade Jee ewes FS oh ee en ge eee Bee ae aes 36 3 3 Reference to self 2 2 a a a a a 36 3 4 _Initializers ooa a 38 3 0 Virtual methods aoa a a a 38 3 6 Private methods a sama e aas D e e a ee 39 3
180. The expression expr expr lt expr3 modifies in place the array denoted by expr replac ing element number expr by the value of expr3 The exception Invalid_argument is raised if the access is out of bounds The value of the whole expression is Strings The expression expr expr returns the value of character number exprs in the string denoted by expr The first character has number 0 the last character has number n 1 where n is the length of the string The exception Invalid_argument is raised if the access is out of bounds The expression expr expr lt expr modifies in place the string denoted by expry replacing character number expr by the value of expr The exception Invalid_argument is raised if the access is out of bounds The value of the whole expression is 6 7 4 Operators Symbols from the class infix symbols as well as the keywords or and amp can appear in infix position between two expressions Symbols from the class prefix symbols can appear in prefix position in front of an expression Infix and prefix symbols do not have a fixed meaning they are simply interpreted as applications of functions bound to the names corresponding to the symbols The expression prefix symbol expr is interpreted as the application prefix symbol expr Similarly the expression expr infix symbol exprs is interpreted as the application infix symbol expr expr Chapter 6 The Objective Caml langua
181. Unix file_descr list Pipes and redirections val pipe unit gt Unix file_descr Unix file_descr val open_process_in string gt Pervasives in_channel val open_process_out string gt Pervasives out_channel val open_process string gt Pervasives in_channel Pervasives out_channel Time val sleep int gt unit Sockets val socket Unix socket_domain gt Unix socket_type gt int gt Unix file_descr val accept Unix file_descr gt Unix file_descr Unix sockaddr val connect Unix file_descr gt Unix sockaddr gt unit val recv Unix file_descr gt string gt int gt int gt Unix msg_flag list gt int val recvfrom Unix file_descr gt 428 string gt int gt int gt Unix msg_flag list gt int Unix sockaddr val send Unix file_descr gt string gt int gt int gt Unix msg_flag list gt int val sendto Unix file_descr gt string gt int gt int gt Unix msg_flag list gt Unix sockaddr gt int val open_connection Unix sockaddr gt Pervasives in_channel Pervasives out_channel Chapter 25 The graphics library The graphics library provides a set of portable drawing primitives Drawing takes place in a separate window that is created when open_graph is called Unix This library is implemented under the X11 windows system Programs that use the graphics library must be linked as follows ocamlc other options graphics cma other files For interactive
182. _positive_int int gt int gt big_int power_big_int_positive_int big_int gt int gt big_int power_int_positive_big_int int gt big_int gt big_int power_big_int_positive_big_int big_int gt big_int gt big_int Exponentiation functions Return the big integer representing the first argument a raised to the power b the second argument Depending on the function a and b can be either small integers or big integers Raise Invalid_argument if b is negative Comparisons and tests val val val val val val val Sign_big_int big_int gt int Return 0 if the given big integer is zero 1 if it is positive and 1 if it is negative compare_big_int big_int gt big_int gt int compare_big_int a b returns 0 if a and b are equal 1 if a is greater than b and 1 if a is smaller than b eq_big_int big_int gt big_int gt bool le_big_int big_int gt big_int gt bool ge_big_int big_int gt big_int gt bool lt_big_int big_int gt big_int gt bool gt_big_int big_int gt big_int gt bool Chapter 22 The num library arbitrary precision rational arithmetic 413 Usual boolean comparisons between two big integers val max_big_int big_int gt big_int gt big_int Return the greater of its two arguments val min_big_int big_int gt big_int gt big_int Return the smaller of its two arguments val num_digits_big_int big_int gt int Return the number of mach
183. address EPERM Operation not permitted EPIPE Broken pipe ERANGE Result too large EROFS Read only file system ESPIPE Invalid seek e g on a pipe ESRCH No such process 373 374 EXDEV Invalid link EWOULDBLOCK Operation would block EINPROGRESS Operation now in progress EALREADY Operation already in progress ENOTSOCK Socket operation on non socket EDESTADDRREQ Destination address required EMSGSIZE Message too long EPROTOTYPE Protocol wrong type for socket ENOPROTOOPT Protocol not available EPROTONOSUPPORT Protocol not supported ESOCKTNOSUPPORT Socket type not supported EOPNOTSUPP Operation not supported on socket EPFNOSUPPORT Protocol family not supported EAFNOSUPPORT Address family not supported by protocol family EADDRINUSE Address already in use EADDRNOTAVAIL Can t assign requested address ENETDOWN Network is down Chapter 21 The unix library Unix system calls ENETUNREACH Network is unreachable ENETRESET Network dropped connection on reset ECONNABORTED Software caused connection abort ECONNRESET Connection reset by peer ENOBUFS No buffer space available EISCONN Socket is already connected ENOTCONN Socket is not connected ESHUTDOWN Can t send after socket shutdown ETOOMANYREFS Too many references can t splice ETIMEDOUT Connection timed out ECONNREFUSED Connection refused EHOSTDOWN Host is down EHOSTUNREACH No route to host ELOOP Too many levels
184. again The typical use is to catch and report exceptions that escape a function application val catch Ca gt b gt a gt b Printexc catch fn x is similar to Printexc print 20 23 but aborts the program with exit code 2 after printing the uncaught exception This function is deprecated the runtime system is now able to print uncaught exceptions as precisely as Printexc catch does Moreover calling Printexc catch makes it harder to track the location of the exception using the debugger or the stack backtrace facility So do not use Printexc catch in new code 20 24 Module Printf Formatted output functions val fprintf Pervasives out_channel gt a Pervasives out_channel unit Pervasives format gt a fprintf outchan format argi argN formats the arguments arg1 to argN according to the format string format and outputs the resulting string on the channel outchan The format is a character string which contains two types of objects plain characters which are simply copied to the output channel and conversion specifications each of which causes conversion and printing of one argument Conversion specifications consist in the character followed by optional flags and field widths followed by one or two conversion character The conversion characters and their meanings are e d i n or N convert an integer argument to signed decimal e u convert an integer argument to unsigned decimal e x convert an
185. ailed information on the behavior of the numerous functions We also suggest to use ocaml browser to see the types of the various functions that are the best documentation for the library itself Programs that use the lab1tk library must be linked as follows ocamlc other options I labltk labltk cma other files ocamlopt other options I labltk labltk cmxa other files Unix The lab1tk library is available for any system with Tcl Tk installed starting from Tcl 7 5 Tk 4 1 up to Tcl Tk 8 3 Beware that some beta versions may have compatibility problems If the library was not compiled correctly try to run again the configure script with the option tkdefs switches where switches is a list of C style inclusion paths leading to the right tcl h and tk h for instance I usr local include tcl8 3 I usr local include tk8 3 A script is installed to make easier the use of the labltk library as toplevel labltk This is a toplevel including the labl1tk library and the path is already set as to allow the use of the various modules It also includes code for the Unix and Str libraries You can use it in place of ocaml Windows The labltk library has been precompiled for use with Tcl Tk 8 3 You must first have it installed on your system It can be downloaded from http www scriptics com products tcltk 8 3 html After installing it you must put the dynamically loaded libraries tc183 d11 and tk83 d11 from the bin directory of the Tcl in
186. aining the same bindings as m plus a binding of x to y If x was already bound in m its previous binding disappears val find key gt at gt a find x mreturns the current binding of x in m or raises Not_found if no such binding exists val remove key gt at gt at remove x mreturns a map containing the same bindings as m except for x which is unbound in the returned map val mem key gt a t gt bool mem x m returns true if m contains a binding for x and false otherwise val iter key gt a gt unit gt a t gt unit iter f m applies f to all bindings in map m f receives the key as first argument and the associated value as second argument The bindings are passed to f in increasing order with respect to the ordering over the type of the keys Only current bindings are presented to f bindings hidden by more recent bindings are not passed to f val map Ca gt b gt at gt bt Chapter 20 The standard library 335 map f m returns a map with same domain as m where the associated value a of all bindings of m has been replaced by the result of the application of f to a The bindings are passed to f in increasing order with respect to the ordering over the type of the keys val mapi key gt a gt b gt at gt bt Same as Map S map 20 18 but the function receives as arguments both the key and the associated value for each binding of the map val fold
187. aise Stream Failure if the stream is empty val empty a t gt unit Return if the stream is empty else raise Stream Failure Chapter 20 The standard library 361 Useful functions val peek a t gt a option Return Some of the first element of the stream or None if the stream is empty val junk a t gt unit Remove the first element of the stream possibly unfreezing it before val count a t gt int Return the current count of the stream elements i e the number of the stream elements discarded val npeek int gt a t gt a list npeek n returns the list of the n first elements of the stream or all its remaining elements if less than n elements are available 20 33 Module String String operations val length string gt int Return the length number of characters of the given string val get string gt int gt char String get s nreturns character number n in string s The first character is character number 0 The last character is character number String length s 1 You can also write s n instead of String get s n Raise Invalid_argument index out of bounds if n is outside the range 0 to String length s 1 val set string gt int gt char gt unit String set s n c modifies string s in place replacing the character number n by c You can also write s n lt c instead of String set s n c Raise Invalid_argument index out of bounds
188. al arrays The Array1 structure provides operations similar to those of Bigarray Genarray 29 1 but specialized to the case of one dimensional arrays The Array2 and Array3 structures below provide operations specialized for two and three dimensional arrays Statically knowing the number of dimensions of the array allows faster operations and more precise static type checking Two dimensional arrays module Array2 sig type Ca b c t Chapter 29 The bigarray library 465 val The type of two dimensional big arrays whose elements have Caml type a representation kind b and memory layout c create a b Bigarray kind gt c Bigarray layout gt int gt int gt a b c t val val val val val val val Array2 create kind layout dim1 dim2 returns a new bigarray of two dimension whose size is dim1 in the first dimension and dim2 in the second dimension kind and layout determine the array element kind and the array layout as described for Bigarray Genarray create 29 1 dimi Ca b c t gt int Return the first dimension of the given two dimensional big array dim2 a b c t gt int Return the second dimension of the given two dimensional big array kind a b c t gt a b Bigarray kind Return the kind of the given big array layout a b c t gt c Bigarray layout Return the layout of the given big ar
189. al_point end let p new functional_point 7 val p functional_point lt obj gt p get_x sine f p move 3 get_x int 10 p get_x 3 int 7 While objects of either class will behave the same objects of their subclasses will be different In a subclass of the latter the method move will keep returning an object of the parent class On the contrary in a subclass of the former the method move will return an object of the subclass Functional update is often used in conjunction with binary methods as illustrated in section 5 2 1 3 14 Cloning objects Objects can also be cloned whether they are functional or imperative The library function 00 copy makes a shallow copy of an object That is it returns an object that is equal to the previous one The instance variables have been copied but their contents are shared Assigning a new value to an Chapter 3 Objects in Caml 55 instance variable of the copy using a method call will not affect instance variables of the original and conversely A deeper assignment for example if the instance variable if a reference cell will of course affect both the original and the copy The type of Oo copy is the following Oo copy lt gt as a gt a lt fun gt The keyword as in that type binds the type variable a to the object type lt gt Therefore Oo copy takes an object with any methods represented by the ellipsis and retu
190. alizable list is a covariant type constructor but not in a list gt a list the left branch of gt is contravariant or a ref ref is non variant Chapter 8 Batch compilation ocamlc 151 Non generalized type variables in a type cause no difficulties inside a given structure or compilation unit the contents of a ml file or an interactive session but they cannot be allowed inside signatures nor in compiled interfaces cmi file because they could be used inconsistently later Therefore the compiler flags an error when a structure or compilation unit defines a value name whose type contains non generalized type variables There are two ways to fix this error e Add a type constraint or a m1i file to give a monomorphic type without type variables to name For instance instead of writing let sort_int_list Sort list lt inferred type a list gt a list with a not generalized write let sort_int_list Sort list lt int list gt int list e If you really need name to have a polymorphic type turn its defining expression into a function by adding an extra parameter For instance instead of writing let map_length List map Array length inferred type a array list gt int list with a not generalized write let map_length lv List map Array length lv Reference to undefined global mod This error appears when trying to link an incomplete or incorrectly ordered set of fi
191. am t gt expression lt fun gt val parse_simple Genlex token Stream t gt expression lt fun gt HH HH HH HH HOH HF HOH OH FH OF OF OF let parse_expression parser lt e parse_expr Stream empty gt gt e val parse_expression Genlex token Stream t gt expression lt fun gt Chapter 1 The core language 23 Composing the lexer and parser we finally obtain a function to read an expression from a character string let read_expression s parse_expression lexer Stream of_string s val read_expression string gt expression lt fun gt read_expression 2 xty expression Prod Const 2 Sum Var x Var y A small puzzle why do we get different results in the following two examples read_expression x 1 expression Diff Var x Const 1 read_expression x 1 Exception Stream Error Answer the generic lexer provided by Genlex recognizes negative integer literals as one integer token Hence x 1 is read as the token Ident x followed by the token Int 1 this sequence does not match any of the parser rules On the other hand the second space in x 1 causes the lexer to return the three expected tokens Ident x then Kwd then Int 1 1 9 Standalone Caml programs All examples given so far were executed under the interactive system Caml code can also be compiled separately and executed non interactively using the batch compilers ocamlc or ocam
192. amlmktop o mytop bigarray cma mytop or if dynamic linking of C libraries is supported on your platform start ocaml and type load bigarray cma 455 456 29 1 Module Bigarray Large multi dimensional numerical ar rays This module implements multi dimensional arrays of integers and floating point numbers thereafter referred to as big arrays The implementation allows efficient sharing of large numerical arrays between Caml code and C or Fortran numerical libraries Concerning the naming conventions users of this module are encouraged to do open Bigarray in their source then refer to array types and operations via short dot notation e g Array1 t or Array2 sub Big arrays support all the Caml ad hoc polymorphic operations e comparisons lt gt lt etc as well as Pervasives compare j e hashing module Hash e and structured input output Pervasives output_value and Pervasives input_value as well as the functions from the Marsha1 20 19 module Element kinds Big arrays can contain elements of the following kinds e IEFE single precision 32 bits floating point numbers Bigarray float32_elt 29 1 e IEEE double precision 64 bits floating point numbers Bigarray float64_elt 29 1 e IEFE single precision 2 32 bits floating point complex numbers Bigarray complex32_elt 29 1 e IEEE double precision 2 64 bits floating point complex numbers Bigarray complex64_e1t 29 1 e 8 bit i
193. an be set with the o option pack Build a bytecode object file cmo file and its associated compiled interface cmi that combines the object files given on the command line making them appear as sub modules of the output cmo file The name of the output cmo file must be given with the o option For instance ocamlc pack o p cmo a cmo b cmo c cmo generates compiled files p cmo and p cmi describing a compilation unit having three sub modules A B and C corresponding to the contents of the object files a cmo b cmo and c cmo These contents can be referenced as P A P B and P C in the remainder of the program pp command Cause the compiler to call the given command as a preprocessor for each source file The output of command is redirected to an intermediate file which is compiled If there are no compilation errors the intermediate file is deleted afterwards The name of this file is built from the basename of the source file with the extension ppi for an interface m1i file and ppo for an implementation m1 file principal Check information path during type checking to make sure that all types are derived in a principal way When using labelled arguments and or polymorphic methods this flag is required to ensure future versions of the compiler will be able to infer types correctly even if internal algorithms change All programs accepted in principal mode are also accepted in default mode with equivalent types but dif
194. an explicit interface m1i file for a file just redirect the standard output of the compiler to a m1i file and edit that file to remove all declarations of unexported names I directory Add the given directory to the list of directories searched for compiled interface files cmi compiled object code files cmo libraries cma and C libraries specified with cclib 1xxx By default the current directory is searched first then the standard library directory Directories added with I are searched after the current directory in the order in which they were given on the command line but before the standard library directory If the given directory starts with it is taken relative to the standard library directory For instance I labltk adds the subdirectory labltk of the standard library to the search path impl filename Compile the file filename as an implementation file even if its extension is not ml intf filename Compile the file filename as an interface file even if its extension is not mli linkall Force all modules contained in libraries to be linked in If this flag is not given unreferenced modules are not linked in When building a library a flag setting the linkall flag forces all subsequent links of programs involving that library to link all the modules contained in the library make runtime Build a custom runtime system in the file specified by option o incorporating the C object files and
195. and link these object files to produce standalone bytecode executable files These executable files are then run by the bytecode interpreter ocamlrun 8 1 Overview of the compiler The ocamlc command has a command line interface similar to the one of most C compilers It accepts several types of arguments and processes them sequentially e Arguments ending in mli are taken to be source files for compilation unit interfaces Inter faces specify the names exported by compilation units they declare value names with their types define public data types declare abstract data types and so on From the file 7 m1i the ocamlc compiler produces a compiled interface in the file x cmi e Arguments ending in ml are taken to be source files for compilation unit implementations Implementations provide definitions for the names exported by the unit and also contain expressions to be evaluated for their side effects From the file z m1 the ocamlc compiler produces compiled object bytecode in the file x cmo If the interface file x mli exists the implementation x m1 is checked against the corresponding compiled interface x cmi which is assumed to exist If no interface z mli is provided the compilation of z ml produces a compiled interface file x cmi in addition to the compiled object code file z cmo The file x cmi produced corresponds to an interface that exports everything that is defined in the implementation z m1 e Arguments ending in cmo are
196. and the element itself as second argument val mapi int gt a gt b gt a array gt b array Same as Array map 20 2 but the function is applied to the index of the element as first argument and the element itself as second argument val fold_left a gt b gt a gt a gt b array gt a Array fold_left f x a computes f f x a 0 a 1 a n 1 where n is the length of the array a val fold_right a gt b gt b gt a array gt b gt b Array fold_right f a x computes f a 0 f a 1 f a n 1 x where n is the length of the array a Sorting val sort a gt a gt int gt a array gt unit Sort an array in increasing order according to a comparison function The comparison function must return 0 if its arguments compare as equal a positive integer if the first is greater and a negative integer if the first is smaller see below for a complete specification For example Pervasives compare 19 2 is a suitable comparison function provided there are no floating point NaN values in the data After calling Array sort the array is sorted in place in increasing order Array sort is guaranteed to run in constant heap space and at most logarithmic stack space The current implementation uses Heap Sort It runs in constant stack space Specification of the comparison function Let a be the array and cmp the comparison fu
197. andle of int gt unit What to do when receiving a signal e Signal_default take the default behavior usually abort the program e Signal_ignore ignore the signal e Signal_handle f call function f giving it the signal number as argument val signal int gt signal_behavior gt signal_behavior Set the behavior of the system on receipt of a given signal The first argument is the signal number Return the behavior previously associated with the signal If the signal number is invalid or not available on your system an Invalid_argument exception is raised val set_signal int gt signal_behavior gt unit Same as Sys signal 20 34 but return value is ignored 366 Signal numbers for the standard POSIX signals val val val val val val val val val val val val val val val Sigabrt int Abnormal termination Sigalrm int Timeout sigfpe int Arithmetic exception sighup int Hangup on controlling terminal sigill int Invalid hardware instruction sigint int Interactive interrupt ctrl C sigkill int Termination cannot be ignored sigpipe int Broken pipe sigquit int Interactive termination sigsegv int Invalid memory reference sigterm int Termination sigusri int Application defined signal 1 sigusr2 int Application defined signal 2 sigchld int Child process terminated sigcont int Chap
198. andle them To use a custom tag for example foo just put foo with some text in your comment as in My comment to show you a custom tag foo this is the text argument to the foo custom tag To handle custom tags you need to define a custom generator as explained in section 15 3 2 15 3 Custom generators OCamldoc operates in two steps 1 analysis of the source files 2 generation of documentation through a documentation generator which is an object of class Odoc_args class_generator Users can provide their own documentation generator to be used during step 2 instead of the default generators All the information retrieved during the analysis step is available through the Odoc_info module which gives access to all the types and functions representing the elements found in the given modules with their associated description The files you can used to define custom generators are installed in the ocamldoc sub directory of the OCaml standard library Chapter 15 The documentation generator ocamldoc 211 15 3 1 The generator class A generator class is a class of type Odoc_args doc_generator It has only one method generator Odoc_info Module t_module list gt unit This method will be called with the list of analysed and possibly merged Odoc_info t_module structures Of course the class can have other methods but the object of this class must be coerced to Odoc_args doc_generator before being passed to the function
199. anne1 20 19 val to_buffer string gt int gt int gt a gt extern_flags list gt int Chapter 20 The standard library 337 Marshal to_buffer buff ofs len v flags marshals the value v storing its byte representation in the string buff starting at character number ofs and writing at most len characters It returns the number of characters actually written to the string If the byte representation of v does not fit in len characters the exception Failure is raised val from_channel Pervasives in_channel gt a Marshal from_channel chan reads from channel chan the byte representation of a structured value as produced by one of the Marshal to_ functions and reconstructs and returns the corresponding value val from_string string gt int gt a Marshal from_string buff ofs unmarshals a structured value like Marshal from_channe1 20 19 does except that the byte representation is not read from a channel but taken from the string buff starting at position ofs val header_size int The bytes representing a marshaled value are composed of a fixed size header and a variable sized data part whose size can be determined from the header Marshal header_size is the size in characters of the header ene Eee ofs is the size in characters of the data part assuming a valid header is stored in buff starting at position ofs Finally Marshal total_size 20 19 buff ofs is the total size in characters of the
200. aracter in a set make it the first or the last character of the set e Matches at beginning of line either at the beginning of the matched string or just after a newline character e Matches at end of line either at the end of the matched string or just before a newline character e infix Alternative between two expressions e Grouping and naming of the enclosed expression e 1 The text matched by the first expression 2 for the second expression and so on up to 9 b Matches word boundaries Quotes special characters The special characters are regexp_case_fold string gt regexp Same as regexp but the compiled expression will match text in a case insensitive way uppercase and lowercase letters will be considered equivalent quote string gt string Str quote s returns a regexp string that matches exactly s and nothing else regexp_string string gt regexp Str regexp_string s returns a regular expression that matches exactly s and nothing else regexp_string_case_fold string gt regexp Str regexp_string_case_fold is similar to Str regexp_string 23 1 but the regexp matches in a case insensitive way String matching and searching val val string_match regexp gt string gt int gt bool string_match r s start tests whether the characters in s starting at position start match the regular expression r The first character of a string has posit
201. aracters actually read val write file_descr gt string gt int gt int gt int write fd buff ofs len writes len characters to descriptor fd taking them from string buff starting at position ofs in string buff Return the number of characters actually written write repeats the writing operation until all characters have been written or an error occurs val single_write file_descr gt string gt int gt int gt int Same as write but attempts to write only once Thus if an error occurs single_write guarantees that no data has been written Interfacing with the standard input output library val in_channel_of_descr file_descr gt Pervasives in_channel Create an input channel reading from the given descriptor The channel is initially in binary mode use set_binary_mode_in ic false if text mode is desired val out_channel_of_descr file_descr gt Pervasives out_channel Create an output channel writing on the given descriptor The channel is initially in binary mode use set_binary_mode_out oc false if text mode is desired val descr_of_in_channel Pervasives in_channel gt file_descr Return the descriptor corresponding to an input channel val descr_of_out_channel Pervasives out_channel gt file_descr Return the descriptor corresponding to an output channel 380 Seeking and truncating type seek_command SEEK_SET indicates positions relative to the beginning of the file SEEK_CUR ind
202. are a gt a gt comparison end module StringSet Set OrderedString module StringSet sig type element OrderedString t type set element list val empty a list val add OrderedString t gt OrderedString t list gt OrderedString t list val member OrderedString t gt OrderedString t list gt bool Chapter 2 The module system 29 end StringSet member bar StringSet add foo StringSet empty bool false 2 4 Functors and type abstraction As in the PrioQueue example it would be good style to hide the actual implementation of the type set so that users of the structure will not rely on sets being lists and we can switch later to another more efficient representation of sets without breaking their code This can be achieved by restricting Set by a suitable functor signature module type SETFUNCTOR functor Elt ORDERED_TYPE gt sig type element Elt t concrete type set abstract val empty set val add element gt set gt set val member element gt set gt bool end module type SETFUNCTOR functor Elt ORDERED_TYPE gt sig type element Elt t type set val empty set val add element gt set gt set val member element gt set gt bool end module AbstractSet Set SETFUNCTOR module AbstractSet SETFUNCTOR module AbstractStringSet AbstractSet OrderedString module AbstractStringSet
203. argN formats the arguments arg1 to argN according to the format string format and outputs the resulting string on the formatter ff The format is a character string which contains three types of objects plain characters and conversion specifications as specified in the printf module and pretty printing indications The pretty printing indication characters are introduced by a character and their meanings are e open a pretty printing box The type and offset of the box may be optionally specified with the following syntax the lt character followed by an optional box type indication then an optional integer offset and the closing gt character Box type is one of h v hv b or hov which stand respectively for an horizontal box a vertical box an 310 horizontal vertical box or an horizontal or vertical box b standing for an horizontal or vertical box demonstrating indentation and hov standing for a regular horizontal or vertical box For instance lt hov 2 gt opens an horizontal or vertical box with indentation 2 as obtained with open_hovbox 2 For more details about boxes see the various box opening functions open_ box close the most recently opened pretty printing box output a good break as with print_cut output a space as with print_space n force a newline as with force_newline output a good break as with print_break The nspaces and offset parameters
204. arge enough to represent the array elements int for 8 and 16 bit integer bigarrays as well as Caml integer bigarrays int32 for 32 bit integer bigarrays int64 for 64 bit integer bigarrays and nativeint for platform native integer bigarrays Finally big arrays of kind int8_unsigned_elt can also be accessed as arrays of characters instead of arrays of small integers by using the kind value char instead of int8_unsigned Array layouts type c_layout See Bigarray fortran_layout 29 1 type fortran_layout To facilitate interoperability with existing C and Fortran code this library supports two different memory layouts for big arrays one compatible with the C conventions the other compatible with the Fortran conventions In the C style layout array indices start at 0 and multi dimensional arrays are laid out in row major format That is for a two dimensional array all elements of row 0 are contiguous in memory followed by all elements of row 1 etc In other terms the array elements at x y and x y 1 are adjacent in memory In the Fortran style layout array indices start at 1 and multi dimensional arrays are laid out in column major format That is for a two dimensional array all elements of column 0 are contiguous in memory followed by all elements of column 1 etc In other terms the array elements at x y and x 1 y are adjacent in memory Each layout style is identified at the type level by the abstract types Bi
205. ary module Pervasive in chapter for more details Their meaning may be changed at any time using let infix op name names When class path evaluates to a class body new class path evaluates to an object containing the instance variables and methods of this class When class path evaluates to a class function new class path evaluates to a function expecting the same number of arguments and returning a new object of this class 116 Immediate object creation Creating directly an object through the object class body end construct is operationally equivalent to defining locally a class myclass object class body end see sections 6 9 2 and following for the syntax of class body and immediately creating a single object from it by new myclass The typing of immediate objects is slightly different from explicitely defining a class in two respects First the inferred object type may contain free type variables Second since the class body of an immediate object will never be extended its self type can be unified with a closed object type Message sending The expression expr method name invokes the method method name of the object denoted by expr If method name is a polymorphic method its type should be known at the invocation site This is true for instance if expr is the name of a fresh object let ident new class path or if there is a type constraint Principality of the derivation can be checked in the princ
206. as Num add_num 22 1 add_num num gt num gt num Addition minus_num num gt num Unary negation num gt num gt num Same as Num sub_num 22 1 sub_num num gt num gt num Subtraction num gt num gt num Same as Num mult_num 22 1 mult_num num gt num gt num Multiplication square_num num gt num Squaring num gt num gt num Same as Num div_nun 22 1 div_num num gt num gt num Division quo_num num gt num gt num Euclidean division quotient mod_num num gt num gt num Euclidean division remainder num gt num gt num Same as Num power_num 22 1 power_num num gt num gt num Exponentiation abs_num num gt num Chapter 22 The num library arbitrary precision rational arithmetic 409 Absolute value val succ_num num gt num succ nis nti val pred_num num gt num pred nis n 1 val incr_num num Pervasives ref gt unit incr ris r r 1 where r is a reference to a number val decr_num num Pervasives ref gt unit decr ris r r 1 where r is a reference to a number val is_integer_num num gt bool Test if a number is an integer The four following functions approximate a number by an integer val integer_num num gt num integer_num n returns the integer closest to n In case of ties rounds towards zero val floor_num num gt num
207. as empty strings in the result type split_result Text of string Delim of string val full_split regexp gt string gt split_result list Same as Str split_delim 23 1 but returns the delimiters as well as the substrings contained between delimiters The former are tagged Delim in the result list the latter are tagged Text For instance full_split regexp ab returns Delim Text ab Delim val bounded_full_split regexp gt string gt int gt split_result list Same as Str bounded_split_delim 23 1 but returns the delimiters as well as the substrings contained between delimiters The former are tagged Delim in the result list the latter are tagged Text Extracting substrings val string_before string gt int gt string string_before s n returns the substring of all characters of s that precede position n excluding the character at position n val string_after string gt int gt string string_after s n returns the substring of all characters of s that follow position n including the character at position n val first_chars string gt int gt string first_chars s n returns the first n characters of s This is the same function as Str string_before val last_chars string gt int gt string last_chars s n returns the last n characters of s 420 Chapter 24 The threads library The threads library allows concurrent programming in Objective Caml
208. ase of tie the regular expression that occurs earlier in the rule is still selected This feature is not intended for use in ordinary lexical analyzers it may facilitate the use of ocamllex as a simple text processing tool 12 2 4 Regular expressions The regular expressions are in the style of lex with a more Caml like syntax gt char A character constant with the same syntax as Objective Caml character constants Match the denoted character Underscore Match any character eof Match the end of the lexer input Note On some systems with interactive input an end of file may be followed by more characters However ocamllex will not correctly handle regular expressions that contain eof followed by something else string A string constant with the same syntax as Objective Caml string constants Match the corresponding sequence of characters character set Match any single character belonging to the given character set Valid character sets are single character constants c ranges of characters c1 c2 all characters between c and c2 inclusive and the union of two or more character sets denoted by concatenation character set Match any single character not belonging to the given character set regexp regexp Difference of character sets Regular expressions regexp and regexps must be character sets defined with or aa single character expression or underscore _ Match
209. ation It is equivalent to print_break 0 0 val print_break int gt int gt unit Inserts a break hint in a pretty printing box print_break nspaces offset indicates that the line may be split a newline character is printed at this point if the contents of the current box does not fit on the current line If the line is split at that point offset is added to the current indentation If the line is not split nspaces spaces are printed val print_flush unit gt unit Flushes the pretty printer all opened boxes are closed and all pending text is displayed val print_newline unit gt unit Equivalent to print_flush followed by a new line val force_newline unit gt unit Forces a newline in the current box Not the normal way of pretty printing you should prefer break hints 302 val print_if_newline unit gt unit Executes the next formatting command if the preceding line has just been split Otherwise ignore the next formatting command Margin val set_margin int gt unit set_margin d sets the value of the right margin to d in characters this value is used to detect line overflows that leads to split lines Nothing happens if d is smaller than 2 If d is too large the right margin is set to the maximum admissible value which is greater than 10710 val get_margin unit gt int Returns the position of the right margin Maximum indentation limit val set_max_indent int gt unit
210. ation units or in struct end module expressions The definition can bind value names type names an exception a module name or a module type name The toplevel system performs the bindings then prints the types and values if any for the names thus defined A phrase may also consist in a open directive see section 6 11 or a value expression sec tion 6 7 Expressions are simply evaluated without performing any bindings and the value of the expression is printed 153 154 Finally a phrase can also consist in a toplevel directive starting with the sharp sign These directives control the behavior of the toplevel they are listed below in section Unix The toplevel system is started by the command ocam1 as follows ocaml options objects interactive mode ocaml options objects scriptfile script mode options are described below objects are filenames ending in cmo or cma they are loaded into the interpreter immediately after options are set scriptfile is any file name not ending in cmo or cma If no scriptfile is given on the command line the toplevel system enters interactive mode phrases are read on standard input results are printed on standard output errors on stan dard error End of file on standard input terminates ocaml see also the quit directive in section On start up before the first phrase is read if the file ocamlinit exists in the current directory its contents are read as a sequence
211. automatically reallocated when more than n characters are stored in the buffer but shrinks back to n characters when reset is called For best performance n should be of the same order of magnitude as the number of characters that are expected to be stored in the buffer for instance 80 for a buffer that holds one output line Nothing bad will happen if the buffer grows beyond that limit however In doubt take n 16 for instance If n is not between 1 and Sys max_string_length 20 34 it will be clipped to that interval val contents t gt string Return a copy of the current contents of the buffer The buffer itself is unchanged val sub t gt int gt int gt string Buffer sub b off len returns a copy of the substring of the current contents of the buffer b starting at offset off of length len bytes May raise Invalid_argument if out of bounds request The buffer itself is unaffected val nth t gt int gt char get the n th character of the buffer Raise Invalid_argument if index out of bounds val length t gt int Return the number of characters currently contained in the buffer val clear t gt unit Empty the buffer val reset t gt unit Empty the buffer and deallocate the internal string holding the buffer contents replacing it with the initial internal string of length n that was allocated by Buffer create 20 3 n For long lived buffers that may have grown a lot reset allows faster recla
212. ayout t gt int gt int gt a b Bigarray fortran_layout Bigarray Array1 t Extract a one dimensional slice of the given three dimensional big array by fixing the last two coordinates The integer parameters are the coordinates of the slice to extract See Bigarray Genarray slice_right 29 1 for more details Array3 slice_right_1 applies only to arrays with Fortran layout val slice_left_2 Ca b Bigarray c_layout t gt int gt a b Bigarray c_layout Bigarray Array2 t Extract a two dimensional slice of the given three dimensional big array by fixing the first coordinate The integer parameter is the first coordinate of the slice to extract See Bigarray Genarray slice_left 29 1 for more details Array3 slice_left_2 applies only to arrays with C layout val slice_right_2 Ca b Bigarray fortran_layout t gt int gt a b Bigarray fortran_layout Bigarray Array2 t Extract a two dimensional slice of the given three dimensional big array by fixing the last coordinate The integer parameter is the coordinate of the slice to extract See Chapter 29 The bigarray library 469 Bigarray Genarray slice_right for more details Array3 slice_right_2 applies only to arrays with Fortran layout val blit a b c t gt Ca b c t gt unit Copy the first big array to the second big array See Bigarray Genarray blit 29 1 for more details val fill Ca b c t gt a gt unit Fill
213. backtrace Trigger the printing of a stack backtrace when an uncaught exception aborts the program This option takes no argument p parser trace Turn on debugging support for ocamlyacc generated parsers When this option is on the pushdown automaton that executes the parsers prints a trace of its actions This option takes no argument s minor_heap_size Size of the minor heap in words major_heap_increment Default size increment for the major heap in words o space_overhead The major GC speed setting max_overhead The heap compaction trigger setting Chapter 10 The runtime system ocamlrun 163 v verbose What GC messages to print to stderr This is a sum of values selected from the following 1 0x001 Start of major GC cycle 2 0x002 Minor collection and major GC slice 4 0x004 Growing and shrinking of the heap 8 0x008 Resizing of stacks and memory manager tables 16 0x010 Heap compaction 32 0x020 Change of GC parameters 64 0x040 Computation of major GC slice size 128 0x080 Calling of finalisation functions 256 0x100 Startup messages loading the bytecode executable file resolving shared libraries l stack_limit The limit in words of the stack size h The initial size of the major heap in words 210 220 230 The multiplier is k M or G for multiplication by and respectively For example on a 32 bit machine under bash the command export OCAMLRUNPARAM
214. be physically modified An instance variable specification will hide any previous specification of an instance variable of the same name Method specification The specification of a method is written method private method name poly typexpr where method name is the name of the method and poly typexpr its expected type possibly polymorphic The flag private indicates whether the method can be accessed from outside the class The polymorphism may be left implicit in method specifications any type variable which is not bound to a class parameter and does not appear elsewhere inside the class specification will be assumed to be polymorphic and made explicit in the resulting method type Writing an explicit polymorphic type will disable this behaviour Several specification for the same method must have compatible types Any non private speci fication of a method forces it to be public Virtual method specification Virtual method specification is written method private virtual method name poly typexpr where method name is the name of the method and poly typexpr its expected type Constraints on type parameters The construct constraint typexpr typexpr forces the two type expressions to be equals This is typically used to specify type parameters they can be that way be bound to a specified type expression 6 9 2 Class expressions Class expressions are the class level equivalent of value expressions they evaluate to classes th
215. big_int Addition of a small integer to a big integer val sub_big_int big_int gt big_int gt big_int Subtraction val pred_big_int big_int gt big_int Predecessor subtract 1 val mult_big_int big_int gt big_int gt big_int Multiplication of two big integers val mult_int_big_int int gt big_int gt big_int Multiplication of a big integer by a small integer val square_big_int big_int gt big_int 412 val val val val val val val val val Return the square of the given big integer sqrt_big_int big_int gt big_int sqrt_big_int a returns the integer square root of a that is the largest big integer r such that r r lt a Raise Invalid_argument if a is negative quomod_big_int big_int gt big_int gt big_int big_int Euclidean division of two big integers The first part of the result is the quotient the second part is the remainder Writing q r quomod_big_int a b we havea q b rand 0 lt r lt bl Raise Division_by_zero if the divisor is zero div_big_int big_int gt big_int gt big_int Euclidean quotient of two big integers This is the first result q of quomod_big_int see above mod_big_int big_int gt big_int gt big_int Euclidean modulus of two big integers This is the second result r of quomod_big_int see above gcd_big_int big_int gt big_int gt big_int Greatest common divisor of two big integers power_int
216. bits bits_of_float 322 325 black bit POT B57 B59 B02 B08 H03 A07 A60 blit_image blue bool bool_of_string borderMode bounded_full_split 419 bounded_split bounded_split_delim 419 bprintf Break break broadcast bscanf Buffer button_down c_layout 458 459 Callback capitalize 359 863 cardinal catch catch_break ceil ceiling_num channel Char char char_of_int 275 chdir check 368 check_suffix 298 chmod choose chop_extension 298 chop_suf fix 298 chown chr 295 chroot 385 classify_float crear 293 B17 B19 15 350 B69 clear_available_units 444 clear_close_on_exec clear_graph clear_nonblock clear_parser close 440 close_box 300 close_graph close_in 282 close_in_noerr 282 close_out 280 close_out_noerr 280 close_process close_process_full close_process_in close_process_out close_tag 305 close_tbox 803 closedir 385 closeTk code 295 INDEX TO THE LIBRARY color 31 combine command 364 compact compare 369 POS 523 B25 833 335 PN 53 B53 BE B63 compare_big_int compare_num Complex complex32 complex32_elt complex64 457 complex64_elt concat 291 P98 B29 557 TH B02 Condition conj connect contains contains_from contents 293 control copy PT BT BTA E0 BN FT 350 BST 359 361 cos 272 cos
217. bolic link to the file source val readlink string gt string Read the contents of a link Polling val select file_descr list gt file_descr list gt file_descr list gt float gt file_descr list file_descr list file_descr list Wait until some input output operations become possible on some channels The three list arguments are respectively a set of descriptors to check for reading first argument for writing second argument or for exceptional conditions third argument The fourth argument is the maximal timeout in seconds a negative fourth argument means no timeout unbounded wait The result is composed of three sets of descriptors those ready for reading first component ready for writing second component and over which an exceptional condition is pending third component 388 Locking type lock_command F_ULOCK Unlock a region F_LOCK Lock a region for writing and block if already locked F_TLOCK Lock a region for writing or fail if already locked F_TEST Test a region for other process locks F_RLOCK Lock a region for reading and block if already locked F_TRLOCK Lock a region for reading or fail if already locked Commands for Unix lockf 21 1 val lockf file_descr gt lock_command gt int gt unit lockf fd cmd size puts a lock on a region of the file opened as fd The region starts at the current read write position for fd as set by Unix 1se
218. bool string method m2 lt n2 b gt bool gt gt b gt bool end In method m1 o must be an object with at least a method n1 itself polymorphic In method m2 the argument of n2 and x must have the same type which is quantified at the same level as a 50 3 12 Using coercions Subtyping is never implicit There are however two ways to perform subtyping The most general construction is fully explicit both the domain and the codomain of the type coercion must be given We have seen that points and colored points have incompatible types For instance they cannot be mixed in the same list However a colored point can be coerced to a point hiding its color method let colored_point_to_point cp cp colored_point gt point val colored_point_to_point colored_point gt point lt fun gt let p new point 3 and q new colored_point 4 blue val p point lt obj gt val q colored_point lt obj gt let 1 p colored_point_to_point q val 1 point list lt obj gt lt obj gt An object of type t can be seen as an object of type t only if t is a subtype of t For instance a point cannot be seen as a colored point p point gt colored_point Type point lt get_offset int get_x int move int gt unit gt is not a subtype of type colored_point lt color string get_offset int get_x int move int gt unit gt Indeed narrowi
219. cation time third arg for a file Times are expressed in seconds from 00 00 00 GMT Jan 1 1970 type interval_timer ITIMER_REAL decrements in real time and sends the signal SIGALRM when expired ITIMER_VIRTUAL decrements in process virtual time and sends SIGVTALRM when expired ITIMER_PROF for profiling decrements both when the process is running and when the system is running on behalf of the process it sends SIGPROF when expired The three kinds of interval timers type interval_timer_status it_interval float Period it_value float Current value of the timer The type describing the status of an interval timer val getitimer interval_timer gt interval_timer_status Return the current status of the given interval timer val setitimer interval_timer gt interval_timer_status gt interval_timer_status setitimer t s sets the interval timer t and returns its previous status The s argument is interpreted as follows s it_value if nonzero is the time to the next timer expiration s it_interval if nonzero specifies a value to be used in reloading it_value when the timer expires Setting s it_value to zero disable the timer Setting s it_interval to zero causes the timer to be disabled after its next expiration 392 User id group id val getuid unit gt int Return the user id of the user executing the process val geteuid unit gt int Return the effective user i
220. ced In particular trigonometric operations cos sin tan have their range reduced to 264 264 Chapter 11 Native code compilation ocamlopt 173 Options for the Sparc architecture The Sparc code generator supports the following addi tional options march v8 Generate SPARC version 8 code march v9 Generate SPARC version 9 code The default is to generate code for SPARC version 7 which runs on all SPARC processors 11 3 Common errors The error messages are almost identical to those of ocamlc See section 8 4 11 4 Running executables produced by ocamlopt Executables generated by ocamlopt are native statically linked stand alone executable files that can be invoked directly They do not depend on the ocamlrun bytecode runtime system During execution of an ocamlopt generated executable the following environment variables are also consulted OCAMLRUNPARAM Same usage as in ocamlrun see section 10 2 except that option 1 is ignored the operating system s stack size limit is used instead and option b is ignored stack backtraces on uncaught exceptions are not printed CAMLRUNPARAM If OCAMLRUNPARAM is not found in the environment then CAMLRUNPARAM will be used instead If CAMLRUNPARAM is not found then the default values will be used 11 5 Compatibility with the bytecode compiler This section lists the known incompatibilities between the bytecode compiler and the native code compiler Except on those point
221. cent parsers we use several intermediate parsing functions to reflect the precedence and associativity of operators Pattern matching over streams is more powerful than on regular data structures as it allows recursive calls to parsing functions inside the patterns for matching sub components of the input stream See the Camlp4 documentation for more details let rec parse_expr parser lt e1 parse_mult e parse_more_adds e1 gt gt e and parse_more_adds e1 parser lt Kwd e2 parse_mult e parse_more_adds Sum e1 e2 gt gt e lt Kwd e2 parse_mult e parse_more_adds Diff e1 e2 gt gt e lt gt gt e1 and parse_mult parser lt e1 parse_simple e parse_more_mults e1 gt gt e and parse_more_mults e1 parser lt Kwd e2 parse_simple e parse_more_mults Prod e1 e2 gt gt e lt Kwd e2 parse_simple e parse_more_mults Quot e1 e2 gt gt e lt gt gt e1 and parse_simple parser lt Ident s gt gt Var s lt Int i gt gt Const float i lt Float f gt gt Const f lt Kwd e parse_expr Kwd gt gt e val parse_expr Genlex token Stream t gt expression lt fun gt val parse_more_adds expression gt Genlex token Stream t gt expression lt fun gt val parse_mult Genlex token Stream t gt expression lt fun gt val parse_more_mults expression gt Genlex token Stre
222. ch keyword in the source code file name line number column number exception Assert_failure of string int int Exception raised when an assertion fails The arguments are the location of the assert keyword in the source code file name line number column number exception Invalid_argument of string Exception raised by library functions to signal that the given arguments do not make sense exception Failure of string Exception raised by library functions to signal that they are undefined on the given arguments exception Not_found Exception raised by search functions when the desired object could not be found exception Out_of_memory Exception raised by the garbage collector when there is insufficient memory to complete the computation exception Stack_overflow Exception raised by the bytecode interpreter when the evaluation stack reaches its maximal size This often indicates infinite or excessively deep recursion in the user s program Not fully implemented by the native code compiler see section ELS exception Sys_error of string Exception raised by the input output functions to report an operating system error exception End_of_file Exception raised by input functions to signal that the end of file has been reached exception Division_by_zero Exception raised by division and remainder operations when their second argument is null Not fully implemented by the native code compiler see section 11
223. character operations are provided in module Char 20 5 val int_of_char char gt int Return the ASCII code of the argument val char_of_int int gt char Return the character with the given ASCII code Raise Invalid_argument char_of_int if the argument is outside the range 0 255 Unit operations val ignore a gt unit Discard the value of its argument and return For instance ignore f x discards the result of the side effecting function f It is equivalent to f x except that the latter may generate a compiler warning writing ignore f x instead avoids the warning String conversion functions val string_of_bool bool gt string Return the string representation of a boolean val bool_of_string string gt bool Convert the given string to a boolean Raise Invalid_argument bool_of_string if the string is not true or false val string_of_int int gt string Return the string representation of an integer in decimal 276 val int_of_string string gt int Convert the given string to an integer The string is read in decimal by default or in hexadecimal if it begins with Ox or OX octal if it begins with Oo or 00 or binary if it begins with Ob or OB Raise Failure int_of_string if the given string is not a valid representation of an integer or if the integer represented exceeds the range of integers representable in type int val string_of_float float gt string Ret
224. cial comment is not already associated to the previous element e The special comment is not the first one of a toplevel module A special comment after an element is associated to this element if there is no blank line or comment between the special comment and the element There are two exceptions for type constructors and record fields in type definitions the asso ciated comment can only be placed after the constructor or field definition without blank lines or other comments between them The following sample interface file foo m1i illustrates the placement rules for comments in mli files The first special comment of the file is the comment associated with the whole module Special comments can be placed between elements and are kept by the OCamldoc tool but are not associated to any element tags in these comments are ignored GRR OOOO I k k kk kk kK kK ak Comments like the one above with more than two asterisks are ignored The comment for function f val f int gt int gt int The continuation of the comment for function f Comment for exception My_exception even with a simple comment between the special comment and the exception Hello I m a simple comment exception My_exception of int gt int int Comment for type weather type weather Rain of int The comment for construtor Rain Sun The comment for constructor Sun
225. ciated value Process handling type process_status WEXITED of int The process terminated normally by exit the argument is the return code WSIGNALED of int The process was killed by a signal the argument is the signal number WSTOPPED of int The process was stopped by a signal the argument is the signal number The termination status of a process type wait_flag WNOHANG do not block if no child has died yet but immediately return with a pid equal to 0 WUNTRACED report also the children that receive stop signals Chapter 21 The unix library Unix system calls 377 val val val val val val val val val val val Flags for Unix waitpid 21 1 execv string gt string array gt a execv prog args execute the program in file prog with the arguments args and the current process environment These execv functions never return on success the current program is replaced by the new one on failure a Unix Unix_error exception is raised execve string gt string array gt string array gt a Same as Unix execv 21 1 except that the third argument provides the environment to the program executed execvp string gt string array gt a Same as Unix execv respectively except that the program is searched in the path execvpe string gt string array gt string array gt a Same as Unix execvp respectively except that the program is searched in the
226. cions are normally written with both the source type and the destination type but in simple cases the source type may be omitted type a wlist Nil Cons of a a wlist Snoc of a wlist a type a wlist Cons of a a wlist Nil Snoc of a wlist a let wlist_of_vlist 1 1 a vlist gt a wlist val wlist_of_vlist a vlist gt a wlist lt fun gt let open_vlist 1 1 a vlist gt gt a vlist val open_vlist a vlist gt gt a vlist lt fun gt fun x gt x gt AI BI C K A B cj gt A B C lt fun gt You may also selectively coerce values through pattern matching let split_cases function Nil Cons _ as x gt A x Snoc _ as x gt Bx 55 val split_cases lt Cons of a Nil Snoc of b gt gt A of gt Cons of a Nil B of gt Snoc of b lt fun gt Chapter 4 Labels and variants 71 When an or pattern composed of variant tags is wrapped inside an alias pattern the alias is given a type containing only the tags enumerated in the or pattern This allows for many useful idioms like incremental definition of functions let num x Num x let evali eval Num x x let rec eval x evall eval x val num a gt gt Num of a lt fun gt val evall
227. cmd sigs changes the set of blocked signals If cmd is SIG_SETMASK blocked signals are set to those in the list sigs If cmd is SIG_BLOCK the signals in sigs are added to the set of blocked signals If cmd is SIG_UNBLOCK the signals in sigs are removed from the set of blocked signals sigprocmask returns the set of previously blocked signals val sigpending unit gt int list Return the set of blocked signals that are currently pending val sigsuspend int list gt unit sigsuspend sigs atomically sets the blocked signals to sigs and waits for a non ignored non blocked signal to be delivered On return the blocked signals are reset to their initial value val pause unit gt unit Wait until a non ignored non blocked signal is delivered Time functions type process_times tms_utime float User time for the process tms_stime float System time for the process tms_cutime float User time for the children processes tms_cstime float System time for the children processes The execution times CPU times of a process type tm tm_sec int Seconds 0 59 tm_min int Minutes 0 59 390 tm_hour int Hours 0 23 tm_mday int Day of month 1 31 tm_mon int Month of year 0 11 tm_year int Year 1900 tm_wday int Day of week Sunday is 0 tm_yday int Day of year 0 365 tm_isdst bool val val val val val val Daylight time sa
228. coercions see section 6 7 5 Chapter 6 The Objective Caml language 119 For instance type a t declares t as an abstract type that is covariant in its parameter this means that if the type 7 is a subtype of the type then 7 t is a subtype of t Similarly type a t declares that the abstract type t is contravariant in its parameter if 7 is subtype of then ao t is subtype of 7 t If no or variance annotation is given the type constructor is assumed invariant in the corresponding parameter For instance the abstract type declaration type a t means that 7 t is neither a subtype nor a supertype of t if T is subtype of The variance indicated by the and annotations on parameters are required only for abstract types For abbreviations variant types or record types the variance properties of the type construc tor are inferred from its definition and the variance annotations are only checked for conformance with the definition The construct constraint ident typexpr allows to specify type parameters Any actual type argument corresponding to the type parameter ident has to be an instance of typexpr more precisely ident and typexpr are unified Type variables of typexpr can appear in the type equation and the type declaration 6 8 2 Exception definitions exception definition exception constr name lof typexpr exception constr name constr Exception definitions add new constructors to the built
229. computes f di dN init wheredi dN are the elements of t in some unspecified order It is not specified what happens if f tries to change t itself count t gt int Count the number of elements in the table count t gives the same result as fold fun _ n gt n 1 t O but does not delay the deallocation of the dead elements stats t gt int int int int int int Return statistics on the table The numbers are in order table length number of entries sum of bucket lengths smallest bucket length median bucket length biggest bucket length The output signature of the functor Weak Make 20 35 module Make functor H Hashtbl HashedType gt S with type data H t Functor building an implementation of the weak hash table structure Chapter 21 The unix library Unix system calls The unix library makes many Unix system calls and system related library functions available to Objective Caml programs This chapter describes briefly the functions provided Refer to sections 2 and 3 of the Unix manual for more details on the behavior of these functions Not all functions are provided by all Unix variants If some functions are not available they will raise Invalid_arg when called Programs that use the unix library must be linked as follows ocamlc other options unix cma other files ocamlopt other options unix cmxa other files For interactive use of the unix library do ocamlmktop o mytop
230. constant expr begin expr end expr typexpr expr expr expr constr expr tag name expr expr expr expr expr expr expr field expr field expr expr with field expr field expr expr argument prefix symbol expr expr infix op expr expr field expr field lt expr expr expr expr expr lt expr expr expr expr expr lt expr if expr then expr else expr while expr do expr done for ident expr to downto expr do expr done expr expr match expr with pattern matching function pattern matching fun multiple matching try expr with pattern matching let rec let binding and let binding in expr new class path object pattern typexpr class field end expr method name inst var name inst var name lt expr expr gt typexpr expr typexpr gt typexpr lt inst var name expr inst var name expr gt assert expr lazy expr expr Jabel name Jabel name expr label name label name expr 108 pattern matching pattern when expr gt expr pattern when expr gt expr multiple matching parameter when expr gt expr let binding pattern expr value name parameter typexpr expr parameter pattern label name label name typexpr label name pattern label name label name typexpr expr label name pattern
231. corresponds to n 0 Lexing lexeme_start lexbuf Return the absolute position in the input text of the beginning of the matched string The first character read from the input text has position 0 Lexing lexeme_end lexbuf Return the absolute position in the input text of the end of the matched string The first character read from the input text has position 0 Chapter 12 Lexer and parser generators ocamllex ocamlyacc 179 entrypoint exp exp lexbuf Where entrypoint is the name of another entry point in the same lexer definition Recursively call the lexer on the given entry point Notice that lexbuf is the last argument Useful for lexing nested comments for example 12 2 6 Variables in regular expressions The as construct is similar to groups as provided by numerous regular expression packages The type of these variables can be string char string option or char option We first consider the case of linear patterns that is the case when all as bound variables are distinct In regexp as ident the type of ident normally is string or string option except when regexp is a character constant an underscore a string constant of length one a character set specification or an alternation of those Then the type of ident is char or char option Option types are introduced when overall rule matching does not imply matching of the bound sub pattern This is in particular the case of regexp as indent and of regexp
232. count as unsafe method deposit x Chapter 5 Advanced examples with classes and modules 75 if zero leq x then unsafe deposit x else raise Invalid_argument deposit end class safe_account object val mutable balance Euro c method balance Euro c method deposit Euro c gt unit method withdraw Euro c gt Euro c end In particular this does not require the knowledge of the implementation of the method deposit To keep trace of operations we extend the class with a mutable field history and a private method trace to add an operation in the log Then each method to be traced is redefined type a operation Deposit of a Retrieval of a type a operation Deposit of a Retrieval of a class account_with_history object self inherit safe_account as super val mutable history method private trace x history lt x history method deposit x self trace Deposit x super deposit x method withdraw x self trace Retrieval x super withdraw x method history List rev history end class account_with_history object val mutable balance Euro c val mutable history Euro c operation list method balance Euro c method deposit Euro c gt unit method history Euro c operation list method private trace Euro c operation gt unit method withdraw Euro c gt Euro c end One may wish to open an account and simultaneously deposit some initia
233. ction cmp merge cmp 11 12 will return a sorted list containting all the elements of 11 and 12 If several elements compare equal the elements of 11 will be before the elements of 12 Not tail recursive sum of the lengths of the arguments 20 18 Module Map Association tables over ordered types This module implements applicative association tables also known as finite maps or dictionaries given a total ordering function over the keys All operations over maps are purely applicative no side effects The implementation uses balanced binary trees and therefore searching and insertion take time logarithmic in the size of the map module type OrderedType sig type t The type of the map keys val compare t gt t gt int A total ordering function over the keys This is a two argument function f such that f e1 e2 is zero if the keys e1 and e2 are equal f e1 e2 is strictly negative if e1 is smaller than e2 and f e1 e2 is strictly positive if e1 is greater than e2 Example a suitable ordering function is the generic structural comparison function Pervasives compare l 334 end Input signature of the functor Map Make 20 18 module type S sig type key The type of the map keys type a t The type of maps from type key to type a val empty at The empty map val is_empty a t gt bool Test whether a map is empty or not val add key gt a gt at gt at add x y mreturns a map cont
234. current values of the memory management counters in a stat record This function examines every heap block to get the statistics val quick_stat unit gt stat 314 val val val val val val val val val val val Same as stat except that live_words live_blocks free_words free_blocks largest_free and fragments are set to 0 This function is much faster than stat because it does not need to go through the heap counters unit gt float float float Return minor_words promoted_words major_words This function is as fast at quick_stat get unit gt control Return the current values of the GC parameters in a control record set control gt unit set r changes the GC parameters according to the control record r The normal usage is Gc set Gc get with Gc verbose 0x00d minor unit gt unit Trigger a minor collection major_slice int gt int Do a minor collection and a slice of major collection The argument is the size of the slice 0 to use the automatically computed slice size In all cases the result is the computed slice size major unit gt unit Do a minor collection and finish the current major collection cycle full_major unit gt unit Do a minor collection finish the current major collection cycle and perform a complete new cycle This will collect all currently unreachable blocks compact unit gt unit Perform a full major col
235. custom block of the size specified in the input stream searching the registered struct custom_operation blocks for one with the same identifier and calling its deserialize function to fill the data part of the custom block 18 9 5 Choosing identifiers Identifiers in struct custom_operations must be chosen carefully since they must identify uniquely the data structure for serialization and deserialization operations In particular con sider including a version number in the identifier this way the format of the data can be changed later yet backward compatible deserialisation functions can be provided Identifiers starting with _ an underscore character are reserved for the Objective Caml runtime system do not use them for your custom data We recommend to use a URL Chapter 18 Interfacing C with Objective Caml 259 http mymachine mydomain com mylibrary version number or a Java style package name com mydomain mymachine mylibrary version number as identifiers to minimize the risk of identifier collision 18 9 6 Finalized blocks Custom blocks generalize the finalized blocks that were present in Objective Caml prior to version 3 00 For backward compatibility the format of custom blocks is compatible with that of finalized blocks and the alloc_final function is still available to allocate a custom block with a given finalization function but default comparison hashing and serialization functions alloc_final n f used maz r
236. cutable file prog is searched in the path The new process has the same environment as the current process val create_process_env string gt string array gt string array gt file_descr gt file_descr gt file_descr gt int create_process_env prog args env new_stdin new_stdout new_stderr works as Unix create_process 21 1 except that the extra argument env specifies the environment passed to the program val open_process_in string gt Pervasives in_channel High level pipe and process management This function runs the given command in parallel with the program The standard output of the command is redirected to a pipe which can be read via the returned input channel The command is interpreted by the shell bin sh cf system val open_process_out string gt Pervasives out_channel Same as Unix open_process_in 21 1 but redirect the standard input of the command to a pipe Data written to the returned output channel is sent to the standard input of the command Warning writes on output channels are buffered hence be careful to call Pervasives flush 19 2 at the right times to ensure correct synchronization val open_process string gt Pervasives in_channel Pervasives out_channel Same as Unix open_process_out but redirects both the standard input and standard output of the command to pipes connected to the two returned channels The input channel is connected to the output of the command and the
237. d val reshape_1 a b c Genarray t gt int gt a b c Array1 t Specialized version of Bigarray reshape for reshaping to one dimensional arrays val reshape_2 Ca b c Genarray t gt int gt int gt a b c Array2 t Specialized version of Bigarray reshape 29 1 for reshaping to two dimensional arrays val reshape_3 Ca b c Genarray t gt int gt int gt int gt a b c Array3 t Specialized version of Bigarray reshape for reshaping to three dimensional arrays 29 2 Big arrays in the Caml C interface C stub code that interface C or Fortran code with Caml code as described in chapter can exploit big arrays as follows 29 2 1 Include file The include file lt caml bigarray h gt must be included in the C stub file It declares the functions constants and macros discussed below Chapter 29 The bigarray library 471 29 2 2 Accessing a Caml bigarray from C or Fortran If v is a Caml value representing a big array the expression Data_bigarray_val v returns a pointer to the data part of the array This pointer is of type void and can be cast to the appropriate C type for the array e g double char 10 etc Various characteristics of the Caml big array can be consulted from C as follows C expression Returns Bigarray_val v gt num_dims number of dimensions Bigarray_val v gt dim i th dimension Bigarray_val v gt flags amp BIGARR
238. d identity int method move int gt unit method notify_observers event gt unit method raise unit method resize int gt unit end class subject richer_window_observer object inherit subject window_observer as super method notify s e if e lt gt Raise then s raise super notify s e end class a richer_window_observer object constraint a lt draw unit raise unit gt method notify a gt event gt unit end We can also create a different kind of observer class subject trace_observer object inherit subject event observer method notify s e Printf printf lt Window d lt s gt n s identity string_of_event e end class a trace_observer object 88 constraint a lt identity int gt method notify a gt event gt unit end and attached several observers to the same object let window new richer_window_subject val window lt notify a gt event gt unit gt richer_window_subject as a lt obj gt window add_observer new richer_window_observer unit window add_observer new trace_observer unit window move 1 window resize 2 lt Window 1 lt Move gt lt Window 1 lt Raise gt Position 1 Size 1 Position 1 Size 1 lt Window 1 lt Resize gt lt Window 1 lt Raise gt Position 1 Size 3 Pos
239. d in applications and parameter order becomes strict o exec file Specify the name of the output file produced by the linker The default output name is a out in keeping with the Unix tradition If the a option is given specify the name of the library produced If the output obj option is given specify the name of the output file produced output obj Cause the linker to produce a C object file instead of an executable file This is useful to wrap Caml code as a C library callable from any C program See chapter 18 section 18 7 5 The name of the output object file is camlprog o by default it can be set with the o option p Generate extra code to write profile information when the program is executed The profile information can then be examined with the analysis program gprof See chapter for more information on profiling The p option must be given both at compile time and at link time Linking object files not compiled with p is possible but results in less precise profiling Unix See the Unix manual page for gprof 1 for more information about the pro files Full support for gprof is only available for certain platforms currently Intel x86 Linux and Alpha Digital Unix On other platforms the p option will result in a less precise profile no call graph information only a time profile Windows The p option does not work under Windows pack Build an object file cmx o file and its associated compiled
240. d parsers type at The type of streams holding values of type a exception Failure Raised by parsers when none of the first components of the stream patterns is accepted exception Error of string Raised by parsers when the first component of a stream pattern is accepted but one of the following components is rejected Stream builders Warning these functions create streams with fast access it is illegal to mix them with streams built with lt gt would raise Failure when accessing such mixed streams val from int gt a option gt at Stream from f returns a stream built from the function f To create a new stream element the function f is called with the current stream count The user function f must return either Some lt value gt for a value or None to specify the end of the stream val of_list a list gt at Return the stream holding the elements of the list in the same order val of_string string gt char t Return the stream of the characters of the string parameter val of_channel Pervasives in_channel gt char t Return the stream of the characters read from the input channel Stream iterator val iter a gt unit gt at gt unit Stream iter f s scans the whole stream s applying function f in turn to each stream element encountered Predefined parsers val next a t gt a Return the first element of the stream and remove it from the stream R
241. d under which the process runs val setuid int gt unit Set the real user id and effective user id for the process val getgid unit gt int Return the group id of the user executing the process val getegid unit gt int Return the effective group id under which the process runs val setgid int gt unit Set the real group id and effective group id for the process val getgroups unit gt int array Return the list of groups to which the user executing the process belongs type passwd_entry pw_name string pw_passwd string pw_uid int pw_gid int pw_gecos string pw_dir string pw_shell string Structure of entries in the passwd database type group_entry gr_name string gr_passwd string gr_gid int gr_mem string array Structure of entries in the groups database val getlogin unit gt string Return the login name of the user executing the process Chapter 21 The unix library Unix system calls 393 val getpwnam string gt passwd_entry Find an entry in passwd with the given name or raise Not_found val getgrnam string gt group_entry Find an entry in group with the given name or raise Not_found val getpwuid int gt passwd_entry Find an entry in passwd with the given user id or raise Not_found val getgrgid int gt group_entry Find an entry in group with the given group id or raise Not_found Internet addre
242. d_formatter val eprintf a formatter unit Pervasives format gt a Same as fprintf above but output on err_formatter val sprintf a unit string Pervasives format gt a Same as printf above but instead of printing on a formatter returns a string containing the result of formatting the arguments Note that the pretty printer queue is flushed at the end of each call to sprintf Chapter 20 The standard library 311 In case of multiple and related calls to sprintf to output material on a single string you should consider using fprintf with a formatter writing to a buffer flushing the buffer at the end of pretty printing returns the desired string You can also use the predefined formatter str_formatter and call flush_str_formatter to get the result val bprintf Buffer t gt a formatter unit Pervasives format gt a Same as sprintf above but instead of printing on a string writes into the given extensible buffer As for sprintf the pretty printer queue is flushed at the end of each call to bprintf In case of multiple and related calls to bprintf to output material on the same buffer b you should consider using fprintf with a formatter writing to the buffer b as obtained by formatter_of_buffer b otherwise the repeated flushes of the pretty printer queue would result in unexpected and badly formatted output val kfprintf formatter gt a gt formatter gt b formatter un
243. dded to the current indentation val open_hvbox int gt unit open_hvbox d opens a new pretty printing box with offset d This box is horizontal vertical it behaves as an horizontal box if it fits on a single line otherwise it behaves as a vertical box When a new line is printed in the box d is added to the current indentation val open_hovbox int gt unit open_hovbox d opens a new pretty printing box with offset d This box is horizontal or vertical break hints inside this box may lead to a new line if there is no more room on the line to print the remainder of the box When a new line is printed in the box d is added to the current indentation Tabulations val open_tbox unit gt unit Opens a tabulation box val close_tbox unit gt unit Closes the most recently opened tabulation box val print_tbreak int gt int gt unit Break hint in a tabulation box print_tbreak spaces offset moves the insertion point to the next tabulation spaces being added to this position Nothing occurs if insertion point is already on a tabulation mark If there is no next tabulation on the line then a newline is printed and the insertion point moves to the first tabulation of the box If a new line is printed offset is added to the current indentation val set_tab unit gt unit Sets a tabulation mark at the current insertion point val print_tab unit gt unit print_tab is equiva
244. de iterators or similar generic operations over a data structure For instance the standard Caml library provides a List map functional that applies a given function to each element of a list and returns the list of the results 14 List map function n gt n 2 1 0 1 2 3 4 int list 1 3 5 7 9 This functional along with a number of other list and array functionals is predefined because it is often useful but there is nothing magic with it it can easily be defined as follows let rec map f 1 match 1 with 1 gt O hd tl gt f hd map f t1 val map a gt b gt a list gt b list lt fun gt 1 4 Records and variants User defined data structures include records and variants Both are defined with the type declara tion Here we declare a record type to represent rational numbers type ratio num int denum int type ratio num int denum int let add_ratio ri r2 num ri num r2 denum r2 num ri denum denum ri denum r2 denum val add_ratio ratio gt ratio gt ratio lt fun gt add_ratio num 1 denum 3 num 2 denum 5 ratio num 11 denum 15 The declaration of a variant type lists all possible shapes for values of that type Each case is identified by a name called a constructor which serves both for constructing values of the variant type and inspecting them by pattern matching Constructor na
245. ding and linking of object files 27 1 Module Dynlink Dynamic loading of bytecode object files 28 The LablTk library Tcl Tk GUI interface 28 1 Module Tk Basic functions and types for LabITk 29 The bigarray library Index to the library s acs aa sacma ee Index of keywords ooa ee 415 415 421 422 423 424 425 426 429 430 439 439 443 443 447 448 455 456 470 Foreword This manual documents the release 3 08 of the Objective Caml system It is organized as follows e Part I An introduction to Objective Caml gives an overview of the language e Part The Objective Caml language is the reference description of the language e Part The Objective Caml tools documents the compilers toplevel system and pro gramming utilities e Part The Objective Caml library describes the modules provided in the standard library e Part Appendix contains an index of all identifiers defined in the standard library and an index of keywords Conventions Objective Caml runs on several operating systems The parts of this manual that are specific to one operating system are presented as shown below Unix This is material specific to the Unix family of operating systems including Linux and MacOS X Windows This is material specific to Microsoft Windows 95 98 ME NT 2000 XP License The Objective Caml system is copyri
246. ds must be compiled with the vmthread option to ocamlc see chapter 8 and be linked as follows ocamlc vmthread other options threads cma other files 421 422 24 1 Module Thread Lightweight threads for Posix 1003 1c and Win32 type t The type of thread handles Thread creation and termination val create a gt b gt a gt t Thread create funct arg creates a new thread of control in which the function application funct arg is executed concurrently with the other threads of the program The application of Thread create returns the handle of the newly created thread The new thread terminates when the application funct arg returns either normally or by raising an uncaught exception In the latter case the exception is printed on standard error but not propagated back to the parent thread Similarly the result of the application funct arg is discarded and not directly accessible to the parent thread val self unit gt t Return the thread currently executing val id t gt int Return the identifier of the given thread A thread identifier is an integer that identifies uniquely the thread It can be used to build data structures indexed by threads val exit unit gt unit Terminate prematurely the currently executing thread val kill t gt unit Terminate prematurely the thread whose handle is given Suspending threads val delay float gt unit delay d suspends the execution of
247. ds that would otherwise be confused as one single identifier literal or keyword Comments Comments are introduced by the two characters with no intervening blanks and terminated by the characters with no intervening blanks Comments are treated as blank characters Comments do not occur inside string or character literals Nested comments are handled correctly 91 92 Identifiers ident letter _ letter 0 9 _ letter A Z a z Identifiers are sequences of letters digits _ the underscore character and the single quote starting with a letter or an underscore Letters contain at least the 52 lowercase and uppercase letters from the ASCII set The current implementation except on MacOS 9 also recognizes as letters all accented characters from the ISO 8859 1 ISO Latin 1 set All characters in an identifier are meaningful The current implementation accepts identifiers up to 16000000 characters in length Integer literals integer literal 0 9 0 9 _ Ox 0x 0 9 A F a 0 9 A F a f _ 0o 00 0 7 0 7 _ 0b OB 0 1 O 1 _ An integer literal is a sequence of one or more digits optionally preceded by a minus sign By default integer literals are in decimal radix 10 The following prefixes select a different radix Prefix Radix Ox OX hexadecimal radix 16 Oo 00 octal radix 8 Ob OB binary radix 2
248. dual object Our next attempt to use it as a string iterator fails The problem here is that quantification was wrongly located this is not the class we want to be polymorphic but the fold method This can be achieved by giving an explicitly polymorphic type in the method definition class intlist l int list object method empty 1 method fold a a gt int gt a gt a gt a fun f accu gt List fold_left f accu 1 end class intlist int list gt object method empty bool method fold a gt int gt a gt a gt a end let 1 new intlist 1 2 3 val 1 intlist lt obj gt 48 l fold fun x y gt x y 0 int 6 l fold fun s x gt s string of ine x string 123 As you can see in the class type shown by the compiler while polymorphic method types must be fully explicit in class definitions appearing immediately after the method name they can be left implicit in class descriptions However the type can be completely omitted in the class definition if it is already known through inheritance or type constraints on self Here is an example of method overriding class intlist_rev 1 object inherit intlist 1 method fold f accu List fold_left f accu List rev 1 end The following idiom separates description and definition class type a iterator object method fold b
249. e a exception Empty Raised when Queue take 20 25 or Queue peek 20 25 is applied to an empty queue val create unit gt at Return a new queue initially empty val add a gt a t gt unit add x q adds the element x at the end of the queue q Chapter 20 The standard library 345 val val val val val val val val val val val val push a gt a t gt unit push is a synonym for add take at gt a take q removes and returns the first element in queue q or raises Empty if the queue is empty pop 2at gt a pop is a synonym for take peek at gt a peek q returns the first element in queue q without removing it from the queue or raises Empty if the queue is empty top at gt a top is a synonym for peek clear a t gt unit Discard all elements from a queue copy a t gt gt at Return a copy of the given queue is_empty a t gt bool Return true if the given queue is empty false otherwise length a t gt int Return the number of elements in a queue iter a gt unit gt a t gt unit iter f q applies f in turn to all elements of q from the least recently entered to the most recently entered The queue itself is unchanged fold Ca gt b gt a gt a gt b t gt a fold f accu q is equivalent to List fold_left f accu 1 where 1 is the list
250. e sharp abbreviations carry an implicit anonymous variable that cannot be explicitly named The closer you get to it is type a c _class a constraint 2a lt m int gt with an extra type variable capturing the open object type 3 13 Functional objects It is possible to write a version of class point without assignments on the instance variables The construct lt gt returns a copy of self that is the current object possibly changing the value of some instance variables class functional_point y object val x y method get_x x method move d lt x x d gt end class functional_point int gt object a val x int method get_x int method move int gt a end let p new functional_point 7 val p functional_point lt obj gt 54 p get_x 3 ant 7 p move 3 get_x int 10 p get_x int 7 Note that the type abbreviation functional_point is recursive which can be seen in the class type of functional_point the type of self is a and a appears inside the type of the method move The above definition of functional_point is not equivalent to the following class bad_functional_point y object val x y method get_x x method move d new functional_point x d end class bad_functional_point int gt object val x int method get_x int method move int gt function
251. e a value belonging to the type token defined by the generated parsing module See the description of ocamlyacc below 175 176 12 1 1 Options The following command line options are recognized by ocamllex o output file Specify the name of the output file produced by ocamllex Default is lerer m1 ocamllex being invoked as ocamllex lexer m11 ml Output code that does not use the Caml built in automata interpreter Instead the automa ton is encoded by Caml functions This option is useful for debugging ocam1llex using it for production lexers is not recommended q Quiet mode ocamllex normally outputs informational messages to standard output They are suppressed if option q is used 12 2 Syntax of lexer definitions The format of lexer definitions is as follows header let ident regexp rule entrypoint Larg argn parse regexp action hn fre regexp action and entrypoint largi argn parse and trailer Comments are delimited by and as in Caml The parse keyword can be replaced by the shortest keyword with the semantic consequences explained below 12 2 1 Header and trailer The header and trailer sections are arbitrary Caml text enclosed in curly braces Either or both can be omitted If present the header text is copied as is at the beginning of the output file and the trailer text at the end Typically the header section contains the open directives required by
252. e 19 2 or the functions of the Marshal 20 19 module create int gt at Weak create n returns a new weak array of length n All the pointers are initially empty Raise Invalid_argument if n is negative or greater than Sys max_array_length 20 34 1 length a t gt int Weak length ar returns the length number of elements of ar set a t gt int gt a option gt unit Weak set ar n Some el sets the nth cell of ar to be a full pointer to el Weak set ar n None sets the nth cell of ar to empty Raise Invalid_argument Weak set if n is not in the range 0 to Weak length 20 35 a 1 get a t gt int gt a option Weak get ar n returns None if the nth cell of ar is empty Some x where x is the value if it is full Raise Invalid_argument Weak get if n is not in the range 0 to Weak length 20 35 a 1 get_copy a t gt int gt a option Weak get_copy ar nreturns None if the nth cell of ar is empty Some x where x is a shallow copy of the value if it is full In addition to pitfalls with mutable values the interesting difference with get is that get_copy does not prevent the incremental GC from erasing the value in its current cycle get may delay the erasure to the next GC cycle Raise Invalid_argument Weak get if n is not in the range 0 to Weak length 20 35 a i check a t gt int gt bool Weak check ar n returns true if the nth cell of ar is full false if
253. e Se aes ees Gee es ee ce cee ee Ge ene te GY Ge ate Cs tee 215 16 3 Commands e lt s ees susa s ER PRG RE Re ee Pa 216 eee tee ee a om Ere hod haa E a a Boe dee Gem bre Sed 217 bs ee od ae He Ga Eee ee ee See ee 219 16 6 The call stack cs e i 6 Seb ee eee DRAKE EE oe be Pee 220 hie be fone hk oe eee oe a eee E 221 iG a eka Be ae wae ae Ge be ee we Rhee 222 16 9 Miscellaneous commands 2 a 225 Bae FF oe eon Gree pinta Seas ee E 225 17 Profiling ocamlprof 227 17 1 Compiling for profiling 2 2 0 2 200000 02 2 ee ee 227 24 te bus aed pos ee oa dee Reto e de ee eS 228 ee piain hp Oh a ged oe OG ee ee aei 228 17 4 Time profiling 2 ee 228 18 Interfacing C with Objective Caml 231 kth das RP a eA eee ee eG 231 OG hae SEE Sie ded Baa kee eG oe Boe ee oa 237 Mtge tee bay eee ean Gada t i eex cs 238 ee ee ee 240 ee 243 Uo he ce Sgn es eG nee oot igs ae ese eve nee pees 247 18 7 Advanced topic callbacks from C to Caml 0 0 0 0 000002 eee 249 Bot ces BS ecw uate ae Re kcal eee a Ge es ee ee ee 253 Sab ee earns 8 Eee ees he a ee ete ee 255 18 10 Building mixed C Caml libraries ocamlmklib 00 4 259 IV The Objective Caml library 263 19 The core library 265 qk ce Race Ss oe OG a eh ee oe ha 265 19 2 Module Pervasives The initially opened module 0 268 20 The standard library 20 1 Module Arg Parsing of command line arguments 2 20 2 Module Array
254. e abstract type a b kind captures this association of a Caml type a for values read or written in the big array and of an element kind b which represents the actual contents of the big array The following predefined values of type kind list all possible associations of Caml types with element kinds float32 float float32_elt kind See Bigarray char float64 float float64_elt kind See Bigarray char complex32 Complex t complex32_elt kind See Bigarray char f complex64 Complex t complex64_elt kind See Bigarray char int8_signed int int8_signed_elt kind See Bigarray char int8_unsigned int int8_unsigned_elt kind See Bigarray char int16_signed int int16_signed_elt kind See Bigarray char int1i6_unsigned int inti6_unsigned_elt kind 458 val val val val val See Bigarray char int int int_elt kind See Bigarray char int32 int32 int32_elt kind See Bigarray char j int64 int64 int64_elt kind See Bigarray char nativeint nativeint nativeint_elt kind See Bigarray char f char char int8_unsigned_elt kind As shown by the types of the values above big arrays of kind float32_elt and float64_elt are accessed using the Caml type float Big arrays of complex kinds complex32_elt complex64_elt are accessed with the Caml type Complex t 20 6 Big arrays of integer kinds are accessed using the smallest Caml integer type l
255. e by the value of expr Of course this instance variable must have been declared mutable The expression lt inst var name expr inst var name expr gt evaluates to a copy of the current object in which the values of instance variables inst var name inst var name have been replaced by the values of the corresponding expressions expr XPIy Virtual method definition Method specification is written method private virtual method name poly typexpr It spec ifies whether the method is public or private and gives its type If the method is intended to be polymorphic the type should be explicit Constraints on type parameters The construct constraint typexpr typexpr forces the two type expressions to be equals This is typically used to specify type parameters they can be that way be bound to a specified type expression Initializers A class initializer initializer expr specifies an expression that will be evaluated when an object will be created from the class once all the instance variables have been initialized 6 9 3 Class definitions class definition class class binding and class binding class binding virtual type parameters class name parameter class type class expr type parameters ident ident Chapter 6 The Objective Caml language 125 A class definition class class binding and class binding is recursive Each class binding defines a class name that
256. e closure of finalisation functions is considered reachable so the following code will not work as expected e let v in Gc finalise fun x gt v Instead you should write e let f fun x gt let v in Gc finalise f v The f function can use all features of O Caml including assignments that make the value reachable again It can also loop forever in this case the other finalisation functions will be called during the execution of f It can call finalise on v or other values to register other functions or even itself It can raise an exception in this case the exception will interrupt whatever the program was doing when the function was called finalise will raise Invalid_argument if v is not heap allocated Some examples of values that are not heap allocated are integers constant constructors booleans the empty array the empty list the unit value The exact list of what is heap allocated or not is implementation dependent Some constant values can be heap allocated but never deallocated during the lifetime of the program for example a list of integer constants this is also implementation dependent You should also be aware that compiler optimisations may duplicate some immutable values for example floating point numbers when stored into arrays so they can be finalised and collected while another copy is still in use by the program The results of calling String make 20 33 String create 20 33 Array make 2
257. e ee er ates de gs ee cae Oy eee ees ens 7 1 Integer literals for types int32 int64 and nativeint bane eoa ES amp ea Hs GR A woe ae Bee gl aoe a 7 3 Recursive definitions of values 2 2 ee Se oe apa ere ae ah hee ee eee ee ee ee a 7 5 Assertion checking 2 ee T6 Lazy evaluation sos ecoa bbe RR RR a Ci Local modules s sses esos Ae ER ee RE RRR bee eee 7 8 Private types 0 ee 7 9 Recursive modules 2 2 ee II The Objective Caml tools 8 Batch compilation ocamlc 8 1 Overview of the compiler 2 0 0 000 eee ee 8 2 Options 63 63 69 73 73 79 85 89 91 91 95 96 99 102 103 107 117 119 126 130 133 135 135 135 135 137 137 137 137 137 138 141 8 3 Modules and the file system 2 2 0 0 0 202 0b eee ee ee ee 149 8 4 Common errors 6 a 149 9 The toplevel system ocaml 153 a wa a ee Rede ne Oe ke eee eee ee 155 Se Se EN ahe ee aCe BL aol Pa A aoe Gy Ba ee oe Sd a 156 gad a gue BOR Se Sw GG ae ee ae lar we gk a 157 9 4 Common errors 2 a 157 9 5 Building custom toplevel systems ocamlmktop 2 28 4 158 Syor te xb hoe St dee E pon a be ee Aw oe ee ae Be ES 159 10 The runtime system ocamlrun 161 Gabe ne RN ee fe Ge wl EUROA ee BY Sel bal gl eh Se ae Be eS BS 161 iat Be B bUl Se Ve Ra Ma ae ee ae a ee a Ee ee Re a a Ha 162 baw home Gee a ere ceeds Ge ets Gee ee a 163 10 4 Common errors ooa 164 11 Native code compi
258. e frame number Select a stack frame by number and describe it The frame currently executing when the program stopped has number 0 its caller has number 1 and so on up the call stack backtrace count bt count Print the call stack This is useful to see which sequence of function calls led to the currently executing frame With a positive argument print only the innermost count frames With a negative argument print only the outermost count frames up count Select and display the stack frame just above the selected frame that is the frame that called the selected frame An argument says how many frames to go up down count Select and display the stack frame just below the selected frame that is the frame that was called by the selected frame An argument says how many frames to go down 16 7 Examining variable values The debugger can print the current value of simple expressions The expressions can involve program variables all the identifiers that are in scope at the selected program point can be accessed Expressions that can be printed are a subset of Objective Caml expressions as described by the following grammar expr lowercase ident capitalized ident lowercase ident integer expr lowercase ident expr integer expr integer expr expr The first two cases refer to a value identifier either unqualified or qualified by the path to the structure that define it
259. e fully implemented and behave as described previously in this chapter 406 Functions Comment fork not implemented use create_process or threads wait not implemented use waitpid waitpid can only wait for a given PID not any child process getppid not implemented meaningless under Windows nice not implemented in_channel_of_descr out_channel_of_descr truncate ftruncate lstat fstat link symlink readlink fchmod chown fchown umask set_nonblock clear_nonblock rewinddir mkfifo select lockf kill pause alarm times getitimer setitimer getuid getgid getgid getegid getgroups setuid setgid getpwnam getpwuid getgrnam getgrgid type socket_domain open_connection establish_server terminal functions tc does not work on sockets under Windows 95 98 ME works fine under NT 2000 XP ditto not implemented not implemented not implemented no links under Windows not implemented not implemented make no sense on a DOS file system not implemented implemented as dummy functions use threads instead of non blocking I O not implemented re open the directory instead not implemented implemented but works only for sockets use threads if you need to wait on other kinds of file descriptors not implemented not implemented no inter process signals in Windows not implemented not implemented always return 1 not implemented not implemented always raise Not_found
260. e methods all initializers along the class hierarchy are evaluated in the order they are introduced 3 10 Parameterized classes Reference cells can be implemented as objects The naive definition fails to typecheck class ref x_init object val mutable x x_init method get x method set y x lt y end Some type variables are unbound in this type class ref a gt object val mutable x a method get a method set a gt unit end The method get has type a where a is unbound The reason is that at least one of the methods has a polymorphic type here the type of the value stored in the reference cell thus either the class should be parametric or the method type should be constrained to a monomorphic type A monomorphic instance of the class could be defined by class ref x_init int object val mutable x x_init method get x method set y x lt y end class ref int gt object val mutable x int method get int method set int gt unit end Note that since immediate objects do not define a class type the have no such restriction let new_ref x_init object val mutable x x_init method get x method set y x lt y end val new_ref a gt lt get a set a gt unit gt lt fun gt On the other hand a class for polymorphic references must explicitly list the type parameters in its d
261. e most common debugger commands are available in the camldebug progname buffer C c C s command step execute the program one step forward C c C k command backstep execute the program one step backward C c C n command next execute the program one step forward skipping over function calls Middle mouse button command display display named value n under mouse cursor support incremental browsing of large data structures 226 C c C p command print print value of identifier at point C c C d command display display value of identifier at point C c C r command run execute the program forward to next breakpoint C c C v command reverse execute the program backward to latest breakpoint C c G L command last go back one step in the command history C c C t command backtrace display backtrace of function calls C c C f command finish run forward till the current function returns C c lt command up select the stack frame below the current frame C c gt command down select the stack frame above the current frame In all buffers in Caml editing mode the following debugger commands are also available C x C a C b command break set a breakpoint at event closest to point C x C a C p command print print value of identifier at point C x C a C d command display display value of identifier at point Chapter 17 Profiling ocamlprof This chapter describes how the
262. e program modules where execution counts have been inserted as comments For instance ocamlprof foo ml prints the source code for the foo module with comments indicating how many times the functions in this module have been called Naturally this information is accurate only if the source file has not been modified since the profiling execution took place The following options are recognized by ocamlprof f dumpfile Specifies an alternate dump file of profiling information F string Specifies an additional string to be output with profiling information By default ocamlprof will annotate programs with comments of the form n where n is the counter value for a profiling point With option F s the annotation will be sn 17 4 Time profiling Profiling with ocamlprof only records execution counts not the actual time spent into each func tion There is currently no way to perform time profiling on bytecode programs generated by ocamlc Chapter 17 Profiling ocamlprof 229 Native code programs generated by ocamlopt can be profiled for time and execution counts using the p option and the standard Unix profiler gprof Just add the p option when compiling and linking the program ocamlopt o myprog p other options files myprog gprof myprog Caml function names in the output of gprof have the following format Module name_function name_unique number Other functions shown are either parts of the Caml run time syst
263. e structure As a consequence a definition may refer to names bound by earlier definitions in the same structure For compatibility with toplevel phrases chapter 9 and with Caml Light an optional is allowed after each definition in a structure The has no semantic meaning Also for compatibility expr is allowed as a component of a structure meaning let _ expr i e evaluate expr for its side effects Chapter 6 The Objective Caml language 131 Value definitions A value definition let rec let binding and let binding bind value names in the same way as a let in expression see section 6 7 1 The value names appearing in the left hand sides of the bindings are bound to the corresponding values in the right hand sides A value definition external value name typexpr external declaration implements value name as the external function specified in external declaration see chapter 18 Type definitions A definition of one or several type components is written type typedef and typedef and consists of a sequence of mutually recursive definitions of type names Exception definitions Exceptions are defined with the syntax exception constr decl or exception constr name constr Class definitions A definition of one or several classes is written class class binding and class binding and consists of a sequence of mutually recursive definitions of class names Class definitions are described more precisely in sectio
264. e structure of the type besides what is stated in the optional type equation The type representation constr decl constr decl describes a variant type The constructor declarations constr decl constr decl describe the constructors associated to this variant type The constructor declaration constr name of typexpr declares the name constr name as a non constant constructor whose argument has type typexpr The constructor declaration constr name declares the name constr name as a constant constructor Constructor names must be capitalized The type representation field decl field decl describes a record type The field dec larations field decl field decl describe the fields associated to this record type The field declaration field name poly typexpr declares field name as a field whose argument has type poly typexpr The field declaration mutable field name poly typexpr behaves similarly in addi tion it allows physical modification over the argument to this field Immutable fields are covariant but mutable fields are neither covariant nor contravariant Both mutable and immutable field may have an explicitly polymorphic type The polymorphism of the contents is statically checked whenever a record value is created or modified Extracted values may have their types instanciated The two components of a type definition the optional equation and the optional representation can be combined independently giving rise t
265. e to print the remainder of the box or if a new line may lead to a new indentation demonstrating the indentation of the box When a new line is printed in the box d is added to the current indentation val close_box unit gt unit Closes the most recently opened pretty printing box Formatting functions val print_string string gt unit print_string str prints str in the current box Chapter 20 The standard library 301 val print_as int gt string gt unit print_as len str prints str in the current box The pretty printer formats str as if it were of length len val print_int int gt unit Prints an integer in the current box val print_float float gt unit Prints a floating point number in the current box val print_char char gt unit Prints a character in the current box val print_bool bool gt unit Prints a boolean in the current box Break hints val print_space unit gt unit print_space is used to separate items typically to print a space between two words It indicates that the line may be split at this point It either prints one space or splits the line It is equivalent to print_break 1 0 val print_cut unit gt unit print_cut is used to mark a good break position It indicates that the line may be split at this point It either prints nothing or splits the line This allows line splitting at the current point without printing spaces or adding indent
266. e usage for ocamlrun is ocamlrun options bytecode executable arg argn The first non option argument is taken to be the name of the file containing the executable bytecode That file is searched in the executable path as well as in the current directory The remaining arguments are passed to the Caml program in the string array Sys argv Element 0 of this array is the name of the bytecode executable file elements 1 to n are the remaining arguments arg to arg As mentioned in chapter 8 the bytecode executable files produced by the ocamlc command are self executable and manage to launch the ocamlrun command on themselves automatically That is assuming caml out is a bytecode executable file caml out arg arg works exactly as ocamlrun caml out arg arg Notice that it is not possible to pass options to ocamlrun when invoking caml out directly Windows Under several versions of Windows bytecode executable files are self executable only if their name ends in exe It is recommended to always give exe names to bytecode executables e g compile with ocamlc o myprog exe rather than ocamlc o myprog 161 162 10 2 Options The following command line options are recognized by ocamlrun b When the program aborts due to an uncaught exception print a detailed back trace of the execution showing where the exception was raised and which function calls were outstanding at this point The back trace is prin
267. e value argv int argn return add_nat_native argv 0 argv 1 argv 2 argv 3 argv 4 argv 5 argv 6 Chapter 18 Interfacing C with Objective Caml 233 The names of the two C functions must be given in the primitive declaration as follows external name type bytecode C function name native code C function name For instance in the case of add_nat the declaration is external add_nat nat gt int gt int gt nat gt int gt int gt int gt int add_nat_bytecode add_nat_native Implementing a user primitive is actually two separate tasks on the one hand decoding the arguments to extract C values from the given Caml values and encoding the return value as a Caml value on the other hand actually computing the result from the arguments Except for very simple primitives it is often preferable to have two distinct C functions to implement these two tasks The first function actually implements the primitive taking native C values as arguments and returning a native C value The second function often called the stub code is a simple wrapper around the first function that converts its arguments from Caml values to C values call the first function and convert the returned C value to Caml value For instance here is the stub code for the input primitive CAMLprim value input value channel value buffer value offset value length return Val_long getblock struct channel channel amp Byte b
268. e without ellipsis This would constrain the type of self be closed and is thus rejected Indeed the type of self cannot be closed this would prevent any further extension of the class Therefore a type error is generated when the unification of this type with another type would result in a closed object type class c object method m 1 end and d object self inherit c method n 2 method as_c self gt c end This expression cannot be coerced to type c lt m int gt it has type lt as_c a m int n int gt but is here used with type c Self type cannot be unified with a closed object type However the most common instance of this problem coercing self to its current class is detected as a special case by the type checker and properly typed class c object self method m self gt c end class c object method m c end This allows the following idiom keeping a list of all objects belonging to a class or its subclasses let all_c ref val all_c _a list ref contents class c m int object self method m m initializer all_c self gt c all_c end class c int gt object method m int end This idiom can in turn be used to retrieve an object whose type has been weakened let rec lookup_obj obj function gt raise Not_found obj 1 gt if obj gt lt gt obj gt lt gt then
269. e_pos returns a point outside of the range 0 size_x Q 1 0 size_y 1 val button_down unit gt bool Return true if the mouse button is pressed false otherwise val read_key unit gt char Wait for a key to be pressed and return the corresponding character Keypresses are queued val key_pressed unit gt bool Return true if a keypress is available that is if read_key would not block Sound val sound int gt int gt unit sound freq dur plays a sound at frequency freq in hertz for a duration dur in milliseconds Chapter 25 The graphics library 437 Double buffering val auto_synchronize bool gt unit By default drawing takes place both on the window displayed on screen and in a memory area the backing store The backing store image is used to re paint the on screen window when necessary To avoid flicker during animations it is possible to turn off on screen drawing perform a number of drawing operations in the backing store only then refresh the on screen window explicitly auto_synchronize false turns on screen drawing off All subsequent drawing commands are performed on the backing store only auto_synchronize true refreshes the on screen window from the backing store as per synchronize then turns on screen drawing back on All subsequent drawing commands are performed both on screen and in the backing store The default drawing mode corresponds to auto_synchronize true
270. eaking and indentation functions Chapter 20 The standard library 307 Multiple formatted output type formatter Abstract data type corresponding to a pretty printer also called a formatter and all its machinery Defining new pretty printers permits the output of material in parallel on several channels Parameters of a pretty printer are local to this pretty printer margin maximum indentation limit maximum number of boxes simultaneously opened ellipsis and so on are specific to each pretty printer and may be fixed independently Given an output channel oc a new formatter writing to that channel is obtained by calling formatter_of_out_channel oc Alternatively the make_formatter function allocates a new formatter with explicit output and flushing functions convenient to output material to strings for instance val formatter_of_out_channel Pervasives out_channel gt formatter formatter_of_out_channel oc returns a new formatter that writes to the corresponding channel oc val std_formatter formatter The standard formatter used by the formatting functions above It is defined as formatter_of_out_channel stdout val err_formatter formatter A formatter to use with formatting functions below for output to standard error It is defined as formatter_of_out_channel stderr val formatter_of_buffer Buffer t gt formatter formatter_of_buffer b returns a new formatter writing to buffer b As usual the formatter has to
271. eakpoint in module module or in the current module if module is not given at the event closest to line line column column break module character Set a breakpoint in module module at the event closest to character number character break address Set a breakpoint at the code address address delete breakpoint numbers Delete the specified breakpoints Without argument all breakpoints are deleted after asking for confirmation info breakpoints Print the list of all breakpoints 16 6 The call stack Each time the program performs a function application it saves the location of the application the return address in a block of data called a stack frame The frame also contains the local variables of the caller function All the frames are allocated in a region of memory called the call stack The command backtrace or bt displays parts of the call stack At any time one of the stack frames is selected by the debugger several debugger commands refer implicitly to the selected frame In particular whenever you ask the debugger for the value of a local variable the value is found in the selected frame The commands frame up and down select whichever frame you are interested in When the program stops the debugger automatically selects the currently executing frame and describes it briefly as the frame command does Chapter 16 The debugger ocamldebug 221 frame Describe the currently selected stack frame fram
272. earch path If filename has the format mod cmi this means you have referenced the compilation unit mod but its compiled interface could not be found Fix compile mod mli or mod ml1 first to create the compiled interface mod cmi If filename has the format mod cmo this means you are trying to load with 1oad a bytecode object file that does not exist yet Fix compile mod m1 first If your program spans several directories this error can also appear because you haven t specified the directories to look into Fix use the directory directive to add the correct directories to the search path This expression has type t but is used with type tz See section Reference to undefined global mod You have neglected to load in memory an implementation for a module with load See section above 9 5 Building custom toplevel systems ocamlmktop The ocamlmktop command builds Objective Caml toplevels that contain user code preloaded at start up The ocamlmktop command takes as argument a set of cmo and cma files and links them with the object files that implement the Objective Caml toplevel The typical use is ocamlmktop o mytoplevel foo cmo bar cmo gee cmo This creates the bytecode file mytoplevel containing the Objective Caml toplevel system plus the code from the three cmo files This toplevel is directly executable and is started by mytoplevel This enters a regular toplevel loop except that the code from foo cmo bar cm
273. eclaration Class type parameters are always listed between and The type parameters must also be bound somewhere in the class body by a type constraint Chapter 3 Objects in Caml 45 class a ref x_init object val mutable x x_init a method get x method set y x lt y end class a ref a gt object val mutable x a method get a method set a gt unit end let r new ref 1 in r set 2 r get int 2 The type parameter in the declaration may actually be constrained in the body of the class def inition In the class type the actual value of the type parameter is displayed in the constraint clause class a ref_succ x_init a object val mutable x x_init 1 method get x method set y x lt y end class a ref_succ 2a gt object constraint a int val mutable x int method get int method set int gt unit end Let us consider a more complex example define a circle whose center may be any kind of point We put an additional type constraint in method move since no free variables must remain unaccounted for by the class type parameters class a circle c a object val mutable center c method center center method set_center c center lt c method move center move int gt unit end class a circle 2a gt object constraint a lt move int gt unit
274. ect Equality between functional values raises Invalid_argument Equality between cyclic data structures does not terminate val lt gt a gt a gt bool Negation of Pervasives 19 2 val lt a gt a gt bool See Pervasives gt 19 2 val gt a gt a gt bool See Pervasives gt 19 2 val lt a gt a gt bool See Pervasives gt 19 2 val gt a gt a gt bool Chapter 19 The core library 269 Structural ordering functions These functions coincide with the usual orderings over integers characters strings and floating point numbers and extend them to a total ordering over all types The ordering is compatible with As in the case of mutable structures are compared by contents Comparison between functional values raises Invalid_argument Comparison between cyclic structures does not terminate val compare a gt a gt int val val val val compare x y returns 0 if x is equal to y a negative integer if x is less than y and a positive integer if x is greater than y The ordering implemented by compare is compatible with the comparison predicates lt and gt defined above with one difference on the treatment of the float value Pervasives nan 19 2I Namely the comparison predicates treat nan as different from any other float value including itself while compare treats nan as equal to itself and les
275. ect numeric IP address AT_CANONNAME Fill the ai_canonname field of the result AT_PASSIVE Set address to any address for use with Unix bind 21 1 Options to Unix getaddrinfo val getaddrinfo string gt string gt getaddrinfo_option list gt addr_info list getaddrinfo host service opts returns a list of Unix addr_info 21 1 records describing socket parameters and addresses suitable for communicating with the given host and service The empty list is returned if the host or service names are unknown or the constraints expressed in opts cannot be satisfied host is either a host name or the string representation of an IP address host can be given as the empty string in this case the any address or the loopback address are used depending whether opts contains AI_PASSIVE service is either a service name or the string representation of a port number service can be given as the empty string in this case the port field of the returned addresses is set to 0 opts is a possibly empty list of options that allows the caller to force a particular socket domain e g IPv6 only or IPv4 only or a particular socket type e g TCP only or UDP only type name_info ni_hostname string Name or IP address of host ni_service string Name of service or port number Chapter 21 The unix library Unix system calls 401 Host and service information returned by Unix getnameinfo type getnameinfo_option
276. ecursive function allocation of an excessively large array or string attempts to build an infinite list or other data structure To help you diagnose this error run your program with the v option to ocamlrun or with the OCAMLRUNPARAM environment variable set to v 63 If it displays lots of Growing stack messages this is probably a looping recursive function If it displays lots of Growing heap messages with the heap size growing slowly this is probably an attempt to construct a data structure with too many infinitely many cells If it displays few Growing heap messages but with a huge increment in the heap size this is probably an attempt to build an excessively large array or string 166 Chapter 11 Native code compilation ocamlopt This chapter describes the Objective Caml high performance native code compiler ocamlopt which compiles Caml source files to native code object files and link these object files to produce standalone executables The native code compiler is only available on certain platforms It produces code that runs faster than the bytecode produced by ocamlc at the cost of increased compilation time and executable code size Compatibility with the bytecode compiler is extremely high the same source code should run identically when compiled with ocamlc and ocamlopt It is not possible to mix native code object files produced by ocamlc with bytecode object files produced by ocamlopt
277. ed marshaled using the Caml functions output_value or Marshal to_ For a custom block those functions first write the identifier of the block as 256 given by the identifier field to the output stream then call the user provided serialize function That function is responsible for writing the data contained in the custom block using the serialize_ functions defined in lt caml intext h gt and listed below The user provided serialize function must then store in its wsize_32 and wsize_64 parameters the sizes in bytes of the data part of the custom block on a 32 bit architecture and on a 64 bit architecture respectively Note You must use CAMLparam to declare v and CAMLreturn to return the result The serialize field can be set to custom_serialize_default in which case the Failure exception is raised when attempting to serialize the custom block e unsigned long deserialize void dst The deserialize field contains a pointer to a C function that is called whenever a custom block with identifier identifier needs to be deserialized un marshaled using the Caml functions input_value or Marshal from_ This user provided function is responsible for reading back the data written by the serialize operation using the deserialize_ functions defined in lt caml intext h gt and listed below It must then rebuild the data part of the custom block and store it at the pointer given as the dst argument Finally it returns the size i
278. ed as a percentage of the memory used for live data The GC will work more use more CPU time and collect blocks more eagerly if space_overhead is smaller Default 80 mutable verbose int This value controls the GC messages on standard error output It is a sum of some of the following flags to print messages on the corresponding events e 0x001 Start of major GC cycle e 0x002 Minor collection and major GC slice e 0x004 Growing and shrinking of the heap e 0x008 Resizing of stacks and memory manager tables e 0x010 Heap compaction e 0x020 Change of GC parameters e 0x040 Computation of major GC slice size e 0x080 Calling of finalisation functions e 0x100 Bytecode executable search at start up e 0x200 Computation of compaction triggering condition Default 0 mutable max_overhead int Heap compaction is triggered when the estimated amount of wasted memory is more than max_overhead percent of the amount of live data If max_overhead is set to 0 heap compaction is triggered at the end of each major GC cycle this setting is intended for testing purposes only If max_overhead gt 1000000 compaction is never triggered Default 500 mutable stack_limit int The maximum size of the stack in words This is only relevant to the byte code runtime as the native code runtime uses the operating system s stack Default 256k The GC parameters are given as a control record val stat unit gt stat Return the
279. ed by an optional type equation then an optional type representation and then a constraint clause The identifier is the name of the type constructor being defined The optional type parameters are either one type variable ident for type constructors with one parameter or a list of type variables ident ident for type constructors with several parameters Each type parameter may be prefixed by a variance constraint resp indicating that the parameter is covariant resp contravariant These type parameters can appear in the type expressions of the right hand side of the definition restricted eventually by a variance constraint i e a covariant parameter may only appear on the right side of a functional arrow more precisely follow the left branch of an even number of arrows and a convariant parameter only the left side left branch of an odd number of arrows 118 The optional type equation typexpr makes the defined type equivalent to the type expression typexpr on the right of the sign one can be substituted for the other during typing If no type equation is given a new type is generated the defined type is incompatible with any other type The optional type representation describes the data structure representing the defined type by giving the list of associated constructors if it is a variant type or associated fields if it is a record type If no type representation is given nothing is assumed on th
280. ed characters follow the lexical conventions of Caml c reads a single character To test the current input character without reading it specify a null field width i e use specification 40c Raise Invalid_argument if the field width specification is greater than 1 C reads a single delimited character delimiters and special escaped characters follow the lexical conventions of Caml f e E g G reads an optionally signed floating point number in decimal notation in the style dddd ddd e E dd F reads a floating point number according to the lexical conventions of Caml hence the decimal point is mandatory if the exponent part is not mentioned B reads a boolean argument true or false b reads a boolean argument for backward compatibility do not use in new programs ld li lu 1x 1X lo reads an int32 argument to the format specified by the second letter decimal hexadecimal etc nd ni nu nx nX no reads a nativeint argument to the format specified by the second letter Ld Li Lu Lx LX Lo reads an int64 argument to the format specified by the second letter range reads characters that matches one of the characters mentioned in the range of characters range or not mentioned in it if the range starts with Returns a string that can be empty if no character in the input matches the range Hence 0 9 returns a string representing a decimal number or an empty string if no decimal dig
281. ed packets socket The type of socket kinds specifying the semantics of communications type sockaddr ADDR_UNIX of string ADDR_INET of inet_addr int The type of socket addresses ADDR_UNIX name is a socket address in the Unix domain name is a file name in the file system ADDR_INET addr port is a socket address in the Internet domain addr is the Internet address of the machine and port is the port number val socket socket_domain gt socket_type gt int gt file_descr Create a new socket in the given domain and with the given kind The third argument is the protocol type 0 selects the default protocol for that kind of sockets val domain_of_sockaddr sockaddr gt socket_domain Return the socket domain adequate for the given socket address val socketpair socket_domain gt socket_type gt int gt file_descr file_descr Create a pair of unnamed sockets connected together Chapter 21 The unix library Unix system calls 395 val accept file_descr gt file_descr sockaddr Accept connections on the given socket The returned descriptor is a socket connected to the client the returned address is the address of the connecting client val bind file_descr gt sockaddr gt unit Bind a socket to an address val connect file_descr gt sockaddr gt unit Connect a socket to an address val listen file_descr gt int gt unit Set up a socket for receiving connection reque
282. efined type of streams of characters or tokens and pattern matching over streams which facilitate the writing of recursive descent parsers for LL 1 languages An example using ocamllex and ocamlyacc is given in chapter Here we will use stream parsers The syntactic support for stream parsers is provided by the Camlp4 preprocessor which can be loaded into the interactive toplevel via the load directive below load camlp4o cma Camlp4 Parsing version 3 07 22 2004 06 16 open Genlex let lexer make_lexer C nyi 4n maw Watts wyn es val lexer char Stream t gt Genlex token Stream t lt fun gt For the lexical analysis phase transformation of the input text into a stream of tokens we use a generic lexer provided in the standard library module Genlex The make_lexer function takes 22 a list of keywords and returns a lexing function that tokenizes an input stream of characters Tokens are either identifiers keywords or literals integer floats characters strings Whitespace and comments are skipped let token_stream lexer Stream of_string 1 0 x val token_stream Genlex token Stream t lt abstr gt Stream next token_stream Genlex token Float 1 Stream next token_stream Genlex token Kwd Stream next token_stream Genlex token Ident x The parser itself operates by pattern matching on the stream of tokens As usual with re cursive des
283. ek 21 1 and extends size bytes forward if size is positive size bytes backwards if size is negative or to the end of the file if size is zero A write lock prevents any other process from acquiring a read or write lock on the region A read lock prevents any other process from acquiring a write lock on the region but lets other processes acquire read locks on it The F_LOCK and F_TLOCK commands attempts to put a write lock on the specified region The F_RLOCK and F_TRLOCK commands attempts to put a read lock on the specified region If one or several locks put by another process prevent the current process from acquiring the lock F_LOCK and F_RLOCK block until these locks are removed while F_TLOCK and F_TRLOCK fail immediately with an exception The F_ULOCK removes whatever locks the current process has on the specified region Finally the F_LTEST command tests whether a write lock can be acquired on the specified region without actually putting a lock It returns immediately if successful or fails otherwise Signals Note installation of signal handlers is performed via the functions Sys signal 20 34 and Sys set_signal 20 34 val kill int gt int gt unit kill pid sig sends signal number sig to the process with id pid Chapter 21 The unix library Unix system calls 389 type sigprocmask_command SIG_SETMASK SIG_BLOCK SIG_UNBLOCK val sigprocmask sigprocmask_command gt int list gt int list sigprocmask
284. em or external C functions linked with the program The output of gprof is described in the Unix manual page for gprof 1 It generally consists of two parts a flat profile showing the time spent in each function and the number of invocation of each function and a hierarchical profile based on the call graph Currently only the Intel x86 Linux and Alpha Digital Unix ports of ocamlopt support the two profiles On other platforms gprof will report only the flat profile with just time information When reading the output of gprof keep in mind that the accumulated times computed by gprof are based on heuristics and may not be exact 230 Chapter 18 Interfacing C with Objective Caml This chapter describes how user defined primitives written in C can be linked with Caml code and called from Caml functions 18 1 Overview and compilation information 18 1 1 Declaring primitives User primitives are declared in an implementation file or struct end module expression using the external keyword external name type C function name This defines the value name name as a function with type type that executes by calling the given C function For instance here is how the input primitive is declared in the standard library module Pervasives external input in_channel gt string gt int gt int gt int input Primitives with several arguments are always curried The C function does not necessarily have the
285. en cond gt expr pattern when condn gt expr Chapter 6 The Objective Caml language 111 Matching proceeds as described before except that if the value matches some pattern pattern which has a guard cond then the expression cond is evaluated in an environment enriched by the bindings performed during matching If cond evaluates to true then expr is evaluated and its value returned as the result of the matching as usual But if cond evaluates to false the matching is resumed against the patterns following pattern Local definitions The let and let rec constructs bind value names locally The construct let pattern expr and and pattern expr in expr evaluates expr expr in some unspecified order then matches their values against the patterns pattern pattern If the matchings succeed expr is evaluated in the environment enriched by the bindings performed during matching and the value of expr is returned as the value of the whole let expression If one of the matchings fails the exception Match_failure is raised An alternate syntax is provided to bind variables to functional values instead of writing let ident fun parameter parameter gt expr in a let expression one may instead write let ident parameter parameter expr Recursive definitions of names are introduced by let rec let rec pattern expr and and pattern expr in expr The only difference with the
286. end until the other thread unlocks the mutex val try_lock t gt bool Same as Mutex lock 24 2 but does not suspend the calling thread if the mutex is already locked just return false immediately in that case If the mutex is unlocked lock it and return true val unlock t gt unit Unlock the given mutex Other threads suspended trying to lock the mutex will restart 24 3 Module Condition Condition variables to synchronize be tween threads Condition variables are used when one thread wants to wait until another thread has finished doing something the former thread waits on the condition variable the latter thread signals the condition when it is done Condition variables should always be protected by a mutex The typical use is if D is a shared data structure m its mutex and c is a condition variable Mutex lock m while some predicate P over D is not satisfied do Condition wait c m done Modify D if the predicate P over D is now satified then Condition signal c Mutex unlock m type t Chapter 24 The threads library 425 The type of condition variables val create unit gt t Return a new condition variable val wait t gt Mutex t gt unit wait c m atomically unlocks the mutex m and suspends the calling process on the condition variable c The process will restart after the condition variable c has been signalled The mutex m is locked again before wait returns
287. eplace_matched string gt string gt string replace_matched repl s returns the replacement text repl in which 1 2 etc have been replaced by the text matched by the corresponding groups in the most recent matching operation s must be the same string that was matched during this matching operation Splitting val split regexp gt string gt string list split r s splits s into substrings taking as delimiters the substrings that match r and returns the list of substrings For instance split regexp t s splits s into blank separated words An occurrence of the delimiter at the beginning and at the end of the string is ignored Chapter 23 The str library regular expressions and string processing 419 val bounded_split regexp gt string gt int gt string list Same as Str split 23 1 but splits into at most n substrings where n is the extra integer parameter val split_delim regexp gt string gt string list Same as Str split 23 1 but occurrences of the delimiter at the beginning and at the end of the string are recognized and returned as empty strings in the result For instance split_delim regexp abc returns abc while split with the same arguments returns abc val bounded_split_delim regexp gt string gt int gt string list Same as Str bounded_split 23 1 but occurrences of the delimiter at the beginning and at the end of the string are recognized and returned
288. eresting for integers or strings there may be some situations where this is desirable The class money above is such an example We show here how to do it for strings 5 2 1 Strings A naive definition of strings as objects could be class ostring s object method get n String get n method set n c String set nc method print print_string s method copy new ostring String copy s end class ostring string gt object 80 method copy ostring method get string gt int gt char method print unit method set string gt int gt char gt unit end However the method copy returns an object of the class string and not an objet of the current class Hence if the class is further extended the method copy will only return an object of the parent class class sub_string s object inherit ostring s method sub start len new sub_string String sub s start len end class sub_string string gt object method copy ostring method get string gt int gt char method print unit method set string gt int gt char gt unit method sub int gt int gt sub_string end As seen in section 3 16 the solution is to use functional update instead We need to create an instance variable containing the representation s of the string class better_string s object val repr s method get n String get n method set n c String set nc method pri
289. es enclose either one character different from and or one of the escape sequences below Sequence Character denoted backslash double quote 2 single quote n linefeed LF r carriage return CR t horizontal tabulation TAB b backspace BS ddd the character with ASCII code ddd in decimal xhh the character with ASCII code hh in hexadecimal String literals string literal string character string character regular char str escape sequence String literals are delimited by double quote characters The two double quotes enclose a sequence of either characters different from and or escape sequences from the table given above for character literals To allow splitting long string literals across lines the sequence newline blanks a at end of line followed by any number of blanks at the beginning of the next line is ignored inside string literals The current implementation places practically no restrictions on the length of string literals Naming labels To avoid ambiguities naming labels cannot just be defined syntactically as the sequence of the three tokens ident and and have to be defined at the lexical level label a z letter 0 9 ks optlabel a z letter 0 9 _ Naming labels come in two flavours label for normal arguments and optlabel for optional ones They are simply distinguished by their first character eithe
290. esentation Externally images are represented as matrices of colors val transp color In matrices of colors this color represent a transparent point when drawing the corresponding image all pixels on the screen corresponding to a transparent pixel in the image will not be modified while other points will be set to the color of the corresponding point in the image This allows superimposing an image over an existing background val make_image color array array gt image Convert the given color matrix to an image Each sub array represents one horizontal line All sub arrays must have the same length otherwise exception Graphic_failure is raised Chapter 25 The graphics library 435 val dump_image image gt color array array Convert an image to a color matrix val draw_image image gt int gt int gt unit Draw the given image with lower left corner at the given point val get_image int gt int gt int gt int gt image Capture the contents of a rectangle on the screen as an image The parameters are the same as for Graphics fill_rect 25 1 val create_image int gt int gt image create_image w h returns a new image w pixels wide and h pixels tall to be used in conjunction with blit_image The initial image contents are random except that no point is transparent val blit_image image gt int gt int gt unit blit_image img x y copies screen pixels into the image img modifying i
291. est t list gt unit Same as Dynlink add_interfaces 27 1 but instead of searching cmi files to find the unit interfaces uses the interface digests given for each unit This way the cmi interface files need not be available at run time The digests can be extracted from cmi files using the extract_crc program installed in the Objective Caml standard library directory val clear_available_units unit gt unit Empty the list of compilation units accessible to dynamically linked programs Chapter 27 The dynlink library dynamic loading and linking of object files 445 Error reporting type linking_error Undefined_global of string Unavailable_primitive of string Uninitialized_global of string type error Not_a_bytecode_file of string Inconsistent_import of string Unavailable_unit of string Unsafe_file Linking error of string linking_error Corrupted_interface of string File_not_found of string Cannot_open_dll of string exception Error of error Errors in dynamic linking are reported by raising the Error exception with a description of the error val error_message error gt string Convert an error description to a printable message 446 Chapter 28 The LablITk library Tcl Tk GUI interface The lab1tk library provides access to the Tcl Tk GUI from Objective Caml programs This inter face is generated in an automated way and you should refer to Tcl Tk books and man pages for de t
292. et and window are themselves inde pendent 58 3 16 Binary methods A binary method is a method which takes an argument of the same type as self The class comparable below is a template for classes with a binary method leq of type a gt bool where the type variable a is bound to the type of self Therefore comparable expands to lt leq a gt bool gt as a We see here that the binder as also allows to write recursive types class virtual comparable object _ a method virtual leq a gt bool end class virtual comparable object a method virtual leq a gt bool end We then define a subclass money of comparable The class money simply wraps floats as comparable objects We will extend it below with more operations There is a type constraint on the class parameter x as the primitive lt is a polymorphic comparison function in Objective Caml The inherit clause ensures that the type of objects of this class is an instance of comparable class money x float object inherit comparable val repr x method value repr method leq p repr lt p value end class money float gt object a val repr float method leq a gt bool method value float end Note that the type money1 is not a subtype of type comparable as the self type appears in contravariant position in the type of method leq Indeed an object m of class money has a method
293. et to an action If extend is true then then binding is added after existing ones otherwise it replaces them breakable should be true when break is to be called inside the action action is called with the fields required set in an eventInfo structure Other fields should not be accessed If action is omitted then existing bindings are removed val bind_class events event list gt extend bool gt breakable bool gt Chapter 28 The LabITk library Tcl Tk GUI interface 453 fields eventField list gt action eventInfo gt unit gt on a Widget widget gt string gt unit Same thing for all widgets of a given class If a widget is given with label on the binding will be removed as soon as it is destroyed val bind_tag events event list gt extend bool gt breakable bool gt fields eventField list gt action eventInfo gt unit gt on a Widget widget gt string gt unit Same thing for all widgets having a given tag val break unit gt unit Used inside a bound action do not call other actions after this one This is only possible if this action was bound with breakable true 454 Chapter 29 The bigarray library The bigarray library implements large multi dimensional numerical arrays These arrays are called big arrays to distinguish them from the standard Caml arrays described in section 20 2 The main differences between big arrays and standard Caml ar
294. ets the module cache Do it if you recompile some interface or get confused about what is in the cache e Modules Search symbol allows to search a symbol either by its name like the bottom line of the viewer or more interestingly by its type Exact type searches for a type with exactly the same information as the pattern variables match only variables Included type allows to give only partial information the actual type may take more arguments and return more results and variables in the pattern match anything In both cases argument and tuple order is irrelevant and unlabeled arguments in the pattern match any label e The Search entry just below the menu bar allows one to search for an identifier in all modules wildcards and allowed If you choose the type option the search is done by type inclusion cf Search Symbol Included type e The Close all button is there to dismiss the windows created by the Detach button By double clicking on it you will quit the browser 14 3 Module browsing You select a module in the leftmost box by either cliking on it or pressing return when it is selected Fast access is available in all boxes pressing the first few letter of the desired name Double clicking double return displays the whole signature for the module Defined identifiers inside the module are displayed in a box to the right of the previous one If you click on one this will either display its contents in ano
295. eturns a fresh custom block of size n words with finalization function f The first word is reserved for storing the custom operations the other n 1 words are available for your data The two parameters used and maz are used to control the speed of garbage collection as described for alloc_custom 18 10 Building mixed C Caml libraries ocamlmklib The ocamlmklib command facilitates the construction of libraries containing both Caml code and C code and usable both in static linking and dynamic linking modes Windows This command is available only under Cygwin but not for the native Win32 port The ocamlmklib command takes three kinds of arguments e Caml source files and object files cmo cmx ml comprising the Caml part of the library e C object files 0 a comprising the C part of the library e Support libraries for the C part 1lib It generates the following outputs e A Caml bytecode library cma incorporating the cmo and ml Caml files given as arguments and automatically referencing the C library generated with the C object files e A Caml native code library cmxa incorporating the cmx and ml Caml files given as argu ments and automatically referencing the C library generated with the C object files e If dynamic linking is supported on the target platform a so shared library built from the C object files given as arguments and automatically referencing the support libraries e A C static library a built
296. execution of Objective Caml programs can be profiled by recording how many times functions are called branches of conditionals are taken 17 1 Compiling for profiling Before profiling an execution the program must be compiled in profiling mode using the ocamlcp front end to the ocamlc compiler see chapter B When compiling modules separately ocamlcp must be used when compiling the modules production of cmo files and can also be used though this is not strictly necessary when linking them together Note Ifa module m1 file doesn t have a corresponding interface mli file then compiling it with ocamlcp will produce object files cmi and cmo that are not compatible with the ones produced by ocamlc which may lead to problems if the cmi or cmo is still around when switching between profiling and non profiling compilations To avoid this problem you should always have a mli file for each m1 file Note To make sure your programs can be compiled in profiling mode avoid using any identifier that begins with __ocaml_prof The amount of profiling information can be controlled through the p option to ocamlcp followed by one or several letters indicating which parts of the program should be profiled a all options f function calls a count point is set at the beginning of function bodies i if then else count points are set in both then branch and else branch 1 while for loops a count point is set at t
297. exeme_start lexeme_start_p 828 Lexing lineto link linking_error List list listen B95 lnot loadfile 443 loadfile_private localtime 890 lock 424 lock_command lockf log log10 logand lognot 324 339 481 logor 821 324 339 logxor lor 271 lower_window lowercase lseek isl lsr lstat lt_big_int 1t_num 1xor 271 magenta 431 mainLoop major major_slice Make B19 B55 555 B70 make 357 859 B61 make_formatter make_image make_lexer make_matrix make_self_init Map nap P9 B30 B37 B57 B3 map_file 462 464 466 269 map2 napi Marshal match_beginning match_end matched_group matched_string Match_failure max 269 max_array_length max_big_int 413 max_elt max_float max_int max_num max_string_length nen 517 B19 B31 B3 B53 59 B70 mem_assoc Ke 482 mem_assq 332 358 memq nerge 553 555 B59 E09 min 269 min_big_int 413 min_elt min_float min_int min_num minor minus_big_int minus_num 408 minus_one mkdir 385 mkf ifo 885 mkt ime 890 mod mod_big_int mod_float mod_num modf modifier mouse_pos 36 moveto msg_flag ma 290 B20 B23 B33 mult_big_int mult_int_big_int mult_num Mutex name_info nan nat_of_num Nativeint nativeint 135 266 346 347 458 nativeint_elt neg 200 B20 B23 B33 neg_infinity
298. expr module module path extended module path 6 10 1 Simple module types The expression modtype path is equivalent to the module type bound to the name modtype path The expression module type denotes the same type as module type 6 10 2 Signatures Signatures are type specifications for structures Signatures sig end are collections of type specifications for value names type names exceptions module names and module type names A structure will match a signature if the structure provides definitions implementations for all the names specified in the signature and possibly more and these definitions meet the type requirements given in the signature For compatibility with Caml Light an optional is allowed after each specification in a signature The has no semantic meaning Value specifications A specification of a value component in a signature is written val value name typexpr where value name is the name of the value and typexpr its expected type Chapter 6 The Objective Caml language 127 The form external value name typexpr external declaration is similar except that it requires in addition the name to be implemented as the external function specified in external declaration see chapter 18 Type specifications A specification of one or several type components in a signature is written type typedef and typedef and consists of a sequence of mutually recursive definitions of type names Each t
299. ey raise Dbm_error Entry already exists replace t gt string gt string gt unit replace db key data inserts the pair key data in the database db If the database already contains data associated with key that data is discarded and silently replaced by the new data remove t gt string gt unit remove db key data removes the data associated with key in db If key has no associated data raise Dbm_error dbm_delete firstkey t gt string See Dbm nextkey nextkey t gt string Enumerate all keys in the given database in an unspecified order firstkey db returns the first key and repeated calls to nextkey db return the remaining keys Not_found is raised when all keys have been enumerated Chapter 26 The dbm library access to NDBM databases 441 val iter string gt string gt a gt t gt unit iter f db applies f to each key data pair in the database db f receives key as first argument and data as second argument 442 Chapter 27 The dynlink library dynamic loading and linking of object files The dynlink library supports type safe dynamic loading and linking of bytecode object files cmo and cma files in a running bytecode program Type safety is ensured by limiting the set of modules from the running program that the loaded object file can access and checking that the running program and the loaded object file have been compiled against the same interfaces for these modules
300. f the module denoted by module path to be referred to by their simple names name instead of path accesses module path name The scope of the open stops at the end of the signature expression Chapter 6 The Objective Caml language 129 Including a signature The expression include module type in a signature performs textual inclusion of the components of the signature denoted by module type It behaves as if the components of the included signature were copied at the location of the include The module type argument must refer to a module type that is a signature not a functor type 6 10 3 Functor types The module type expression functor module name module type gt module type is the type of functors functions from modules to modules that take as argument a module of type module type and return as result a module of type module type The module type module type can use the name module name to refer to type components of the actual argument of the functor No restrictions are placed on the type of the functor argument in particular a functor may take another functor as argument higher order functor 6 10 4 The with operator Assuming module type denotes a signature the expression module type with mod constraint and mod constraint denotes the same signature where type equations have been added to some of the type specifications as described by the constraints following the with keyword The con straint type type pa
301. f_string lxm 184 a PLUS 262 MINUS 2 TIMES DIV BG LPAREN li A RPAREN eof raise Eof Here is the main program that combines the parser with the lexer File calc ml let _ try let lexbuf Lexing from_channel stdin in while true do let result Parser main Lexer token lexbuf in print_int result print_newline flush stdout done with Lexer Eof gt exit 0 To compile everything execute ocamllex lexer mll generates lexer ml ocamlyacc parser mly generates parser ml and parser mli ocamlc c parser mli ocamlc c lexer ml ocamlc c parser ml ocamlc c calc ml ocamlc o calc lexer cmo parser cmo calc cmo 12 7 Common errors ocamllex transition table overflow automaton is too big The deterministic automata generated by ocamllex are limited to at most 32767 transitions The message above indicates that your lexer definition is too complex and overflows this limit This is commonly caused by lexer definitions that have separate rules for each of the alphabetic keywords of the language as in the following example rule token parse keywordi KWD1 keyword2 KWD2 keyword100 KWD100 A Z 2a Z PA Z 2g Z 290 799 2 22 as id IDENT id Chapter 12 Lexer and parser generators ocamllex ocamlyacc 185 To keep the generated automata small rewrite those definitions with only one general iden tifier rule followed by a
302. face type Ca b t val val val val val val val The type of hash tables from type a to type b create int gt a b t Hashtbl create n creates a new empty hash table with initial size n For best results n should be on the order of the expected number of elements that will be in the table The table grows as needed so n is just an initial guess clear a b t gt unit Empty a hash table add a b t gt a gt b gt unit Hashtbl add tbl x y adds a binding of x to y in table tbl Previous bindings for x are not removed but simply hidden That is after performing Hashtbl remove 20 12 tbl x the previous binding for x if any is restored Same behavior as with association lists copy Ca b t gt Ca b t Return a copy of the given hashtable find Ca b t gt a gt b Hashtbl find tbl x returns the current binding of x in tbl or raises Not_found if no such binding exists find_all a b t gt a gt b list Hashtbl find_all tbl x returns the list of all data associated with x in tbl The current binding is returned first then the previous bindings in reverse order of introduction in the table mem a b t gt a gt bool Hashtbl mem tbl x checks if x is bound in tbl 318 val val val val val remove a b t gt a gt unit Hashtbl remove tbl x removes the current bindin
303. ferent binary signatures and this may slow down type checking yet this is a good idea to use it once before publishing source code rectypes Allow arbitrary recursive types during type checking By default only recursive types where the recursion goes through an object type are supported thread Compile or link multithreaded programs in combination with the system threads library described in chapter unsafe Turn bound checking off on array and string accesses the v i and s i constructs Programs compiled with unsafe are therefore slightly faster but unsafe anything can happen if the program accesses an array or string outside of its bounds 148 use runtime runtime name Generate a bytecode executable file that can be executed on the custom runtime system runtime name built earlier with ocamlc make runtime runtime name See section 18 1 6 for more information v Print the version number of the compiler and the location of the standard library directory then exit verbose Print all external commands before they are executed in particular invocations of the C compiler and linker in custom mode Useful to debug C library problems version Print the version number of the compiler in short form e g 3 06 then exit vmthread Compile or link multithreaded programs in combination with the VM level threads library described in chapter w warning list Enable or disable warnings according to the argument warn
304. ferred to using the dot notation that is identifiers qualified by a structure name For instance PrioQueue insert in a value context is the function insert defined inside the structure PrioQueue Similarly PrioQueue queue in a type context is the type queue defined in PrioQueue PrioQueue insert PrioQueue empty 1 hello string PrioQueue queue PrioQueue Node 1 hello PrioQueue Empty PrioQueue Empty 2 2 Signatures Signatures are interfaces for structures A signature specifies which components of a structure are accessible from the outside and with which type It can be used to hide some components of a structure e g local function definitions or export some components with a restricted type For instance the signature below specifies the three priority queue operations empty insert and extract but not the auxiliary function remove_top Similarly it makes the queue type abstract by not providing its actual representation as a concrete type module type PRIOQUEUE sig type priority int still concrete type a queue now abstract val empty a queue val insert a queue gt int gt a gt a queue val extract a queue gt int a a queue exception Queue_is_empty end module type PRIOQUEUE sig type priority int type a queue Chapter 2 The module system 27 val empty a queue val insert a queue gt int gt a gt
305. fies the file permissions in case the file must be created Pervasives open_out 19 2 and Pervasives open_out_bin 19 2 are special cases of this function flush out_channel gt unit Flush the buffer associated with the given output channel performing all pending writes on that channel Interactive programs must be careful about flushing standard output and standard error at the right time flush_all unit gt unit Flush all open output channels ignore errors output_char out_channel gt char gt unit Write the character on the given output channel output_string out_channel gt string gt unit Write the string on the given output channel output out_channel gt string gt int gt int gt unit output oc buf pos len writes len characters from string buf starting at offset pos to the given output channel oc Raise Invalid_argument output if pos and len do not designate a valid substring of buf output_byte out_channel gt int gt unit Write one 8 bit integer as the single character with that code on the given output channel The given integer is taken modulo 256 output_binary_int out_channel gt int gt unit Write one integer in binary format 4 bytes big endian on the given output channel The given integer is taken modulo 232 The only reliable way to read it back is through the Pervasives input_binary_int 19 2 function The format is compatible across all machines for a
306. flushed into the output device of the formatter Chapter 20 The standard library 305 val close_tag unit gt unit close_tag closes the most recently opened tag t In addition the print_close_tag function of the formatter is called with t as argument The marker mark_close_tag t will be flushed into the output device of the formatter val set_tags bool gt unit set_tags b turns on or off the treatment of tags default is off val set_print_tags bool gt unit val set_mark_tags bool gt unit set_print_tags b turns on or off the printing of tags while set_mark_tags b turns on or off the output of tag markers val get_print_tags unit gt bool val get_mark_tags unit gt bool Return the current status of tags printing and tags marking Redirecting formatter output val set_formatter_out_channel Pervasives out_channel gt unit Redirect the pretty printer output to the given channel val set_formatter_output_functions string gt int gt int gt unit gt unit gt unit gt unit set_formatter_output_functions out flush redirects the pretty printer output to the functions out and flush The out function performs the pretty printer output It is called with a string s a start position p and a number of characters n it is supposed to output characters p top n 1 of s The flush function is called whenever the pretty printer is flushed using print_flush or print_newline val get_fo
307. from the C object files In addition the following options are recognized cclib ccopt I linkall These options are passed as is to ocamlc or ocamlopt See the documentation of these commands 260 pthread rpath R Wl rpath W1 R These options are passed as is to the C compiler Refer to the documentation of the C compiler custom Force the construction of a statically linked library only even if dynamic linking is supported failsafe Fall back to building a statically linked library if a problem occurs while building the shared library e g some of the support libraries are not available as shared libraries Ldir Add dir to the search path for support libraries 1lib ocamlc cmd Use cmd instead of ocamlc to call the bytecode compiler ocamlopt cmd Use cmd instead of ocamlopt to call the native code compiler o output Set the name of the generated Caml library ocamlmklib will generate output cma and or output cmxa If not specified defaults to a oc outputc Set the name of the generated C library ocamlmklib will generate liboutputc so if shared libraries are supported and liboutputc a If not specified defaults to the output name given with o Example Consider a Caml interface to the standard libz C library for reading and writing compressed files Assume this library resides in usr local zlib This interface is composed of a Caml part zip cmo zip cmx and a C part zipstubs o containing the
308. function definitions let open_paren prec op_prec if prec gt op_prec then print_string in let close_paren prec op_prec if prec gt op_prec then print_string in let rec print prec exp prec is the current precedence match exp with Const c gt print_float c Chapter 1 The core language 21 Var v gt print_string v Sum f g gt open_paren prec 0 print 0 f print_string print 0 g close_paren prec 0 Ditt Cl g gt open_paren prec 0 print 0 f print_string print 1 g close_paren prec 0 Prod f g gt open_paren prec 2 print 2 f print_string print 2 g close_paren prec 2 Quot f g gt open_paren prec 2 print 2 f print_string print 3 g close_paren prec 2 in print 0 exp val print_expr expression gt unit lt fun gt HH HH HHH HH H FH HH FH OH FH OF OF let e Sum Prod Const 2 0 Var x Const 1 0 val e expression Sum Prod Const 2 Var x Const 1 print_expr e print_newline 2 x 1 unit print_expr deriv e x print_newline 2 1 0 x 02 unit Parsing transforming concrete syntax into abstract syntax is usually more delicate Caml offers several tools to help write parsers on the one hand Caml versions of the lexer generator Lex and the parser generator Yacc see chapter 1 which handle LALR 1 languages using push down automata on the other hand a pred
309. g The type of character strings 265 266 type float The type of floating point numbers type bool false true The type of booleans truth values type unit The type of the unit value type exn The type of exception values type a array The type of arrays whose elements have type a type a list of a a list The type of lists whose elements have type a type a option None Some of a The type of optional values of type a type int32 The type of signed 32 bit integers See the Int32 20 13 module type int64 The type of signed 64 bit integers See the Int64 20 14 module type nativeint The type of signed platform native integers 32 bits on 32 bit processors 64 bits on 64 bit processors See the Nativeint 20 20 module type a b c d format4 The type of format strings a is the type of the parameters of the format d is the result type for the printf style function b is the type of the first argument given to a and t printing functions see module Printf 20 24 and c is the result type of these functions type a lazy_t This type is used to implement the Lazy 20 15 module It should not be used directly Chapter 19 The core library 267 Predefined exceptions exception Match_failure of string int int Exception raised when none of the cases of a pattern matching apply The arguments are the location of the mat
310. g an abstract datatype with user defined finalization comparison hashing serialization and deserial ization functions atttached 18 2 3 Pointers outside the heap Any word aligned pointer to an address outside the heap can be safely cast to and from the type value This includes pointers returned by malloc and pointers to C variables of size at least one word obtained with the amp operator Caution if a pointer returned by malloc is cast to the type value and returned to Caml explicit deallocation of the pointer using free is potentially dangerous because the pointer may still be accessible from the Caml world Worse the memory space deallocated by free can later be reallocated as part of the Caml heap the pointer formerly pointing outside the Caml heap now points inside the Caml heap and this can confuse the garbage collector To avoid these problems it is preferable to wrap the pointer in a Caml block with tag Abstract_tag or Custom_tag 18 3 Representation of Caml data types This section describes how Caml data types are encoded in the value type Chapter 18 Interfacing C with Objective Caml 239 18 3 1 Atomic types Caml type Encoding int Unboxed integer values char Unboxed integer values ASCII code float Blocks with tag Double_tag string Blocks with tag String_tag int32 Blocks with tag Custom_tag int64 Blocks with tag Custom_tag nativeint Blocks with tag Custom_tag
311. g of x in tbl restoring the previous binding if it exists It does nothing if x is not bound in tbl replace a b t gt a gt b gt unit Hashtbl replace tbl x y replaces the current binding of x in tbl by a binding of x to y If x is unbound in tbl a binding of x to y is added to tbl This is functionally equivalent to Hashtbl remove 20 12 tbl x followed by Hashtbl add 20 12 tbl x y iter Ca gt b gt unit gt a b t gt unit Hashtbl iter f tbl applies f to all bindings in table tbl f receives the key as first argument and the associated value as second argument Each binding is presented exactly once to f The order in which the bindings are passed to f is unspecified However if the table contains several bindings for the same key they are passed to f in reverse order of introduction that is the most recent binding is passed first fold Ca gt b gt c gt c gt Ca b t gt c gt c Hashtbl fold f tbl init computes f KN dN f ki d1 init where ki KN are the keys of all bindings in tbl and d1 dN are the associated values Each binding is presented exactly once to f The order in which the bindings are passed to f is unspecified However if the table contains several bindings for the same key they are passed to f in reverse order of introduction that is the most recent binding is passed first length Ca b t gt int Hashtbl length tbl
312. g operations Array p array operations List p list operations StdLabels p labelized versions of the above 3 modules Sort p sorting and merging lists Hashtbl p hash tables and hash functions Random p pseudo random number generator Set p sets over ordered types Map p association tables over ordered types Do p useful functions on objects Stack p last in first out stacks Queue p first in first out queues Buffer p string buffers that grow on demand Lazy p delayed evaluation Weak p references that don t prevent objects from being garbage collected Arithmetic Complex p Complex numbers Int32 p operations on 32 bit integers Int64 p operations on 64 bit integers Nativeint p operations on platform native integers Input output Format pretty printing with automatic indentation and line breaking Marshal marshaling of data structures Printf formatting printing functions Scanf formatted input functions Digest MD5 message digest Parsing Genlex p a generic lexer over streams Lexing p the run time library for lexers generated by ocamllex Parsing p the run time library for parsers generated by ocamlyacc Stream p basic functions over streams Chapter 20 The standard library 287 System interface Arg p parsing of command line arguments Callback p registering Caml functions to be called from C Filename p operations on file names Gc p memory management control and statistics Printexc p a catch all exception handler Sys
313. garray c_layout 29 1 and fortran_layout respectively Chapter 29 The bigarray library 459 type a layout The type a layout represents one of the two supported memory layouts C style if a is Bigarray c_layout 29 1 Fortran style if a is Bigarray fortran_layout 29 1 Supported layouts The abstract values c_layout and fortran_layout represent the two supported layouts at the level of values val c_layout c_layout layout val fortran_layout fortran_layout layout Generic arrays of arbitrarily many dimensions module Genarray sig type Ca b c t The type Genarray t is the type of big arrays with variable numbers of dimensions Any number of dimensions between 1 and 16 is supported The three type parameters to Genarray t identify the array element kind and layout as follows e the first parameter a is the Caml type for accessing array elements float int int32 int64 nativeint e the second parameter b is the actual kind of array elements float32_elt float64_elt int8_signed_elt int8_unsigned_elt etc e the third parameter c identifies the array layout c_layout or fortran_layout For instance float float32_elt fortran_layout Genarray t is the type of generic big arrays containing 32 bit floats in Fortran layout reads and writes in this array use the Caml type float val create Ca b Bigarray kind gt c Bigarray layout gt int array gt a b c
314. ge 115 The table below lists the symbols defined in the initial environment and their initial meaning Operator Initial meaning Integer addition infix Integer subtraction prefix Integer negation Integer multiplication Integer division Raise Division_by_zero if second argument is zero mod Integer modulus Raise Division_by_zero if second argument is zero land Bitwise logical and on integers lor Bitwise logical or on integers lxor Bitwise logical exclusive or on integers 1sl Bitwise logical shift left on integers lsr Bitwise logical shift right on integers asr Bitwise arithmetic shift right on integers Floating point addition infix Floating point subtraction prefix Floating point negation Floating point multiplication Floating point division xk Floating point exponentiation List concatenation String concatenation Dereferencing return the current contents of a reference Reference assignment update the reference given as first argument with the value of the second argument Structural equality test lt gt Structural inequality test Physical equality test I Physical inequality test lt Test less than lt Test less than or equal gt Test greater than gt Test greater than or equal 6 7 5 Objects Object creation See the description of the standard libr
315. ge 0 255 The three components are packed in an int OxRRGGBB where RR are the two hexadecimal digits for the red component GG for the green component BB for the blue component val rgb int gt int gt int gt color rgb r g b returns the integer encoding the color with red component r green component g and blue component b r g and b are in the range 0 255 val set_color color gt unit Set the current drawing color val background color See Graphics foreground val foreground color Default background and foreground colors usually either black foreground on a white background or white foreground on a black background Graphics clear_graph fills the screen with the background color The initial drawing color is foreground Some predefined colors val black color val white color val red color val green color val blue color val yellow color val cyan color val magenta color 432 Point and line drawing val val val val val val val val val val val val val plot int gt int gt unit Plot the given point with the current drawing color plots int int array gt unit Plot the given points with the current drawing color point_color int gt int gt color Return the color of the given point in the backing store see Double buffering below moveto int gt int gt unit Position the current point rmovet
316. ght 1996 1997 1998 1999 2000 2001 2002 2003 2004 Institut National de Recherche en Informatique et en Automatique INRIA INRIA holds all ownership rights to the Objective Caml system The Objective Caml system is open source and can be freely redistributed See the file LICENSE in the distribution for licensing information The present documentation is copyright 2004 Institut National de Recherche en Informa tique et en Automatique INRIA The Objective Caml documentation and user s manual may be reproduced and distributed in whole or in part subject to the following conditions 7 8 Foreword e The copyright notice above and this permission notice must be preserved complete on all complete or partial copies e Any translation or derivative work of the Objective Caml documentation and user s manual must be approved by the authors in writing before distribution e If you distribute the Objective Caml documentation and user s manual in part instructions for obtaining the complete version of this manual must be included and a means for obtaining a complete version provided e Small portions may be reproduced as illustrations for reviews or quotes in other works without this permission notice if proper citation is given Availability The complete Objective Caml distribution can be accessed via the Web site http caml inria fr This Web site contains a lot of additional information on Objective Caml Part I An in
317. gnized by ocamldep I directory Add the given directory to the list of directories searched for source files If a source file foo ml mentions an external compilation unit Bar a dependency on that unit s interface bar cmi is generated only if the source for bar is found in the current directory or in one of the directories specified with I Otherwise Bar is assumed to be a module from the standard library and no dependencies are generated For programs that span multiple directories it is recommended to pass ocamldep the same I options that are passed to the compiler native Generate dependencies for a pure native code program no bytecode version When an implementation file m1 file has no explicit interface file mli file ocamldep generates dependencies on the bytecode compiled file cmo file to reflect interface changes This can cause unnecessary bytecode recompilations for programs that are compiled to native code only The flag native causes dependencies on native compiled files cmx to be generated instead of on cmo files This flag makes no difference if all source files have explicit mli interface files 187 188 13 2 A typical Makefile Here is a template Makefile for a Objective Caml program OCAMLC ocamlc OCAMLOPT ocamlopt OCAMLDEP ocamldep INCLUDES all relevant I options here OCAMLFLAGS INCLUDES add other options for ocamlc here OCAMLOPTFLAGS INCLUDES add other options for ocamlopt
318. gram forward or backward starting at the current time The execution will stop either when specified by the command or when a breakpoint is encountered run Execute the program forward from current time Stops at next breakpoint or when the program terminates reverse Execute the program backward from current time Mostly useful to go to the last breakpoint encountered before the current time Chapter 16 The debugger ocamldebug 219 step count Run the program and stop at the next event With an argument do it count times backstep count Run the program backward and stop at the previous event With an argument do it count times next count Run the program and stop at the next event skipping over function calls With an argument do it count times previous count Run the program backward and stop at the previous event skipping over function calls With an argument do it count times finish Run the program until the current function returns start Run the program backward and stop at the first event before the current function invocation 16 4 4 Time travel You can jump directly to a given time without stopping on breakpoints using the goto command As you move through the program the debugger maintains an history of the successive times you stop at The last command can be used to revisit these times each last command moves one step back through the history That is useful mainly to undo commands such as ste
319. gt b gt c gt a list gt b list gt c list List rev_map2 f 1 gives the same result as List rev 20 17 List map2 20 17 1 but is tail recursive and more efficient val fold_left2 a gt b gt c gt a gt a gt b list gt c list gt a List fold_left2 f a b1 bn c1 cn isf f f a bi cl b2 c2 bn cn Raise Invalid_argument if the two lists have different lengths val fold_right2 a gt b gt c gt c gt a list gt b list gt c gt c List fold_right2 f al an b1 bn cisf al b1 f a2 b2 f an bn c Raise Invalid_argument if the two lists have different lengths Not tail recursive Chapter 20 The standard library 331 List scanning val for_all a gt bool gt a list gt bool for_all p at an checks if all elements of the list satisfy the predicate p That is it returns p a1 amp amp p a2 amp amp amp amp p an val exists a gt bool gt a list gt bool exists p a1 an checks if at least one element of the list satisfies the predicate p That is it returns p a1 p a2 II II p an val for_all2 a gt b gt bool gt a list gt b list gt bool Same as List for_al1 20 17 but for a two argument predicate Raise Invalid_argument if the two lists have different lengths val exists2 a g
320. gt bool See Arith_status set_error_when_null_denominator set_error_when_null_denominator bool gt unit Get or set the flag null_denominator When on attempting to create a rational with a null denominator raises an exception When off rationals with null denominators are accepted Initially on get_normalize_ratio unit gt bool See Arith_status set_normalize_ratio set_normalize_ratio bool gt unit Get or set the flag normalize_ratio When on rational numbers are normalized after each operation When off rational numbers are not normalized until printed Initially off get_normalize_ratio_when_printing unit gt bool See Arith_status set_normalize_ratio_when_printing set_normalize_ratio_when_printing bool gt unit Get or set the flag normalize_ratio_when_printing When on rational numbers are normalized before being printed When off rational numbers are printed as is without normalization Initially on get_approx_printing unit gt bool See Arith_status set_approx_printing set_approx_printing bool gt unit Get or set the flag approx_printing When on rational numbers are printed as a decimal approximation When off rational numbers are printed as a fraction Initially off get_floating_ precision unit gt int See Arith_status set_floating_precision set_floating precision int gt unit Get or set the parameter floating_precision This parameter is the number of digi
321. gt int get string gt int gt char set string gt int gt char gt unit create int gt string make int gt char gt string copy string gt string sub string gt pos int gt len int gt string fill string gt pos int gt len int gt char gt unit blit src string gt src_pos int gt dst string gt dst_pos int gt len int gt unit val val val val val val val val val val val val val val concat sep string gt string list gt string iter f char gt unit gt string gt unit escaped string gt string index string gt char gt int rindex string gt char gt int index_from string gt int gt char gt int rindex_from string gt int gt char gt int contains string gt char gt bool contains_from string gt int gt char gt bool rcontains_from string gt int gt char gt bool uppercase string gt string lowercase string gt string capitalize string gt string uncapitalize string gt string type t string val val val val compare t gt t gt int unsafe_get string gt int gt char unsafe_set string gt int gt char gt unit unsafe_blit src string gt src_pos int gt dst string gt dst_pos int gt len int gt unit val end unsafe_fill string gt pos int gt len int gt char gt unit 360 20 32 Module Stream Streams an
322. gt unit method notify_observers b gt unit end The difficulty usually relies in defining instances of the pattern above by inheritance This can be done in a natural and obvious manner in Ocaml as shown on the following example manipulating windows type event Raise Resize Move type event Raise Resize Move let string_of_event function Raise gt Raise Resize gt Resize Move gt Move val string_of_event event gt string lt fun gt 86 let count ref 0 val count int ref contents 0 class observer window_subject let id count succ count count in object self inherit observer event subject val mutable position 0 method identity id method move x position lt position x self notify_observers Move method draw Printf printf Position d n position end class a window_subject object b constraint a lt notify b gt event gt unit gt val mutable observers a list val mutable position int method add_observer a gt unit method draw unit method identity int method move int gt unit method notify_observers event gt unit end class subject window_observer object inherit subject event observer method notify s e s draw end class a window_observer object constraint a lt draw unit gt method n
323. h count counters create 290 293 819 3441 1356 357 359 36 1 368 369 422 42 4 425 459 463 165 LOT create_alarn create_image create_matrix 290 create_process 886 create_process_env current 289 current_dir_name 298 current_point current_x current_y curveto cyan data 369 data_size ATT Dbm 439 Dbm_error 440 decr 283 decr_nun default_available_units 444 delay delete_alarm descr_of_in_channel descr_of_out_channel destroy diff Digest 297 dim dim1 165 67 dim2 65 67 dim3 467 dims dir_handle 385 dirname 299 display_mode aiv 290 B20 B23 E33 div_big_int div_num 408 Division_by_zero doc 288 domain_of_sockaddr draw_arc draw_char draw_circle draw_ellipse draw_image draw_poly draw_poly_line draw_rect 432 draw_segments draw_string 33 dummy _pos dump_image dup dup2 Dynlink elements elt 352 Empty 478 empty 334 B53 B60 end_of_input 348 End_of_file 267 environment eprintf epsilon_float eq_big_int eq_num equal err_formatter Error error 375 445 error_message escaped 295 359 362 establish_server 398 Event event eventField eventInfo executable_name execv execve execvp 377 426 execvpe exists 331 354 B58 exists2 Exit 268 exit exn 266 exp 273 27 extern_f lags
324. hannel Note that close_out may raise Sys_error if the operating system signals an error when flushing or closing close_out_noerr out_channel gt unit Same as close_out but ignore all errors set_binary_mode_out out_channel gt bool gt unit set_binary_mode_out oc true sets the channel oc to binary mode no translations take place during output set_binary_mode_out oc false sets the channel oc to text mode depending on the operating system some translations may take place during output For instance under Windows end of lines will be translated from n to r n This function has no effect under operating systems that do not distinguish between text mode and binary mode General input functions val open_in string gt in_channel Open the named file for reading and return a new input channel on that file positionned at the beginning of the file Raise Sys_error if the file could not be opened Chapter 19 The core library 281 val val val val val open_in_bin string gt in_channel Same as Pervasives open_in 19 2 but the file is opened in binary mode so that no translation takes place during reads On operating systems that do not distinguish between text mode and binary mode this function behaves like Pervasives open_in 19 2 open_in_gen open_flag list gt int gt string gt in_channel Open the named file for reading as above The extra arguments mode and perm specify the opening
325. hapter 29 The bigarray library 461 The array a must have exactly N dimensions and all coordinates must lie inside the array bounds as described for Genarray get otherwise Invalid_arg is raised If N gt 3 alternate syntax is provided you can write a i1 i2 iN lt v instead of Genarray set a i1 iNI v The syntax a lt v with one two or three coordinates is reserved for updating one two and three dimensional arrays as described below val sub_left Ca b Bigarray c_layout t gt int gt int gt a b Bigarray c_layout t Extract a sub array of the given big array by restricting the first left most dimension Genarray sub_left a ofs len returns a big array with the same number of dimensions as a and the same dimensions as a except the first dimension which corresponds to the interval ofs ofs len 1 of the first dimension of a No copying of elements is involved the sub array and the original array share the same storage space In other terms the element at coordinates li1 iN of the sub array is identical to the element at coordinates li1 ofs iN of the original array a Genarray sub_left applies only to big arrays in C layout Raise Invalid_arg if ofs and len do not designate a valid sub array of a that is if ofs lt 0 or len lt 0 or ofs len gt Genarray nth_dim a 0 val sub_right Ca b Bigarray fortran_layout t gt int gt int gt a
326. haracter on standard output and flush standard output This can be used to simulate line buffering of standard output Output functions on standard error val prerr_char char gt unit Print a character on standard error val prerr_string string gt unit Print a string on standard error val prerr_int int gt unit Print an integer in decimal on standard error val prerr_float float gt unit Print a floating point number in decimal on standard error val prerr_endline string gt unit Print a string followed by a newline character on standard error and flush standard error val prerr_newline unit gt unit Print a newline character on standard error and flush standard error 278 Input functions on standard input val read_line unit gt string Flush standard output then read characters from standard input until a newline character is encountered Return the string of all characters read without the newline character at the end val read_int unit gt int Flush standard output then read one line from standard input and convert it to an integer Raise Failure int_of_string if the line read is not a valid representation of an integer val read_float unit gt float Flush standard output then read one line from standard input and convert it to a floating point number The result is unspecified if the line read is not a valid representation of a floating point number Ge
327. he custom cclib and ccopt options as if they had been provided on the command line unless the noautolink option is given c Compile only Suppress the linking phase of the compilation Source code files are turned into compiled files but no executable file is produced This option is useful to compile modules separately Chapter 8 Batch compilation ocamlc 145 cc ccomp Use ccomp as the C linker called by ocamlc custom and as the C compiler for compiling c source files cclib lLlibname Pass the 1libname option to the C linker when linking in custom runtime mode see the custom option This causes the given C library to be linked with the program ccopt option Pass the given option to the C compiler and linker when linking in custom runtime mode see the custom option For instance ccopt Ldir causes the C linker to search for C libraries in directory dir custom Link in custom runtime mode In the default linking mode the linker produces bytecode that is intended to be executed with the shared runtime system ocamlrun In the custom runtime mode the linker produces an output file that contains both the runtime system and the bytecode for the program The resulting file is larger but it can be executed directly even if the ocamlrun command is not installed Moreover the custom runtime mode enables static linking of Caml code with user defined C functions as described in chapter 18 Unix
328. he beginning of execution chdir string gt unit Change the current working directory of the process getcwd unit gt string Return the current working directory of the process readdir string gt string array Return the names of all files present in the given directory Names denoting the current directory and the parent directory and in Unix are not returned Each string in the result is a file name rather than a complete path There is no guarantee that the name strings in the resulting array will appear in any specific order they are not in particular guaranteed to appear in alphabetical order Chapter 20 The standard library 365 val interactive bool Pervasives ref This reference is initially set to false in standalone programs and to true if the code is being executed under the interactive toplevel system ocam1 val os_type string Operating system currently executing the Caml program One of e Unix for all Unix versions including Linux and Mac OS X e Win32 for MS Windows OCaml compiled with MSVC or Mingw e Cygwin for MS Windows OCaml compiled with Cygwin val word_size int Size of one word on the machine currently executing the Caml program in bits 32 or 64 val max_string_length int Maximum length of a string val max_array_length int Maximum length of an array Signal handling type signal_behavior Signal_default Signal_ignore Signal_h
329. he beginning of the loop body m match branches a count point is set at the beginning of the body of each branch t try with branches a count point is set at the beginning of the body of each branch 227 228 For instance compiling with ocamlcp p film profiles function calls if then else loops and pattern matching Calling ocamlcp without the p option defaults to p fm meaning that only function calls and pattern matching are profiled Note Due to the implementation of streams and stream patterns as syntactic sugar it is hard to predict what parts of stream expressions and patterns will be profiled by a given flag To profile a program with streams we recommend using ocamlcp p a 17 2 Profiling an execution Running a bytecode executable file that has been compiled with ocamlcp records the execution counts for the specified parts of the program and saves them in a file called ocamlprof dump in the current directory The ocamlprof dump file is written only if the program terminates normally by calling exit or by falling through It is not written if the program terminates with an uncaught exception If a compatible dump file already exists in the current directory then the profiling information is accumulated in this dump file This allows for instance the profiling of several executions of a program on different inputs 17 3 Printing profiling information The ocamlprof command produces a source listing of th
330. he first argument is the required precision The second argument is the number to approximate Num approx_num_f ix 22 1 uses decimal notation the first argument is the number of digits after the decimal point approx_num_exp uses scientific exponential notation the first argument is the number of digits in the mantissa num_of_string string gt num Convert a string to a number Coercions between numerical types val val val val val val val val val int_of_num num gt int num_of_int int gt num nat_of_num num gt Nat nat num_of_nat Nat nat gt num num_of_big_int Big_int big_int gt num big_int_of_num num gt Big_int big_int ratio_of_num num gt Ratio ratio num_of_ratio Ratio ratio gt num float_of_num num gt float Chapter 22 The num library arbitrary precision rational arithmetic 411 22 2 Module Big_int Operations on arbitrary precision integers Big integers type big_int are signed integers of arbitrary size type big_int The type of big integers val zero_big_int big_int The big integer 0 val unit_big_int big_int The big integer 1 Arithmetic operations val minus_big_int big_int gt big_int Unary negation val abs_big_int big_int gt big_int Absolute value val add_big_int big_int gt big_int gt big_int Addition val succ_big_int big_int gt big_int Successor add 1 val add_int_big_int int gt big_int gt
331. he regular expression val lexeme_char lexbuf gt int gt char Lexing lexeme_char lexbuf i returns character number i in the matched string val lexeme_start lexbuf gt int Lexing lexeme_start lexbuf returns the offset in the input stream of the first character of the matched string The first character of the stream has offset 0 val lexeme_end lexbuf gt int Lexing lexeme_end lexbuf returns the offset in the input stream of the character following the last character of the matched string The first character of the stream has offset 0 val lexeme_start_p lexbuf gt position Like lexeme_start but return a complete position instead of an offset val lexeme_end_p lexbuf gt position Like lexeme_end but return a complete position instead of an offset Chapter 20 The standard library 329 Miscellaneous functions val flush_input lexbuf gt unit Discard the contents of the buffer and reset the current position to 0 The next use of the lexbuf will trigger a refill 20 17 Module List List operations Some functions are flagged as not tail recursive A tail recursive function uses constant stack space while a non tail recursive function uses stack space proportional to the length of its list argument which can be a problem with very long lists When the function takes several list arguments an approximate formula giving stack usage in some unspecified constant unit is shown in parentheses The
332. hell is used to pass the arguments to the debugged program You can therefore use wildcards shell variables and file redirections inside the arguments To debug programs that read from standard input it is recommended to redirect their input from a file using set arguments lt input file otherwise input to the program and input to the debugger are not properly separated and inputs are not properly replayed when running the program backwards 16 8 2 How programs are loaded The loadingmode variable controls how the program is executed set loadingmode direct The program is run directly by the debugger This is the default mode set loadingmode runtime The debugger execute the Objective Caml runtime ocamlrun on the program Rarely useful moreover it prevents the debugging of programs compiled in custom runtime mode set loadingmode manual The user starts manually the program when asked by the debugger Allows remote debugging see section 16 8 6 Chapter 16 The debugger ocamldebug 223 16 8 3 Search path for files The debugger searches for source files and compiled interface files in a list of directories the search path The search path initially contains the current directory and the standard library directory The directory command adds directories to the path Whenever the search path is modified the debugger will clear any information it may have cached about the files directory directorynames Add the give
333. hod clear to manually erase all copies class backup object self mytype val mutable copy None method save copy lt Some lt gt method restore match copy with Some x gt x None gt self method clear copy lt None end Chapter 3 Objects in Caml 57 class backup object a val mutable copy a option method clear unit method restore a method save unit end class a backup_ref x object inherit a ref x inherit backup end class a backup_ref 2a gt object b val mutable copy b option val mutable x a method clear unit method get a method restore b method save unit method set a gt unit end let p new backup_ref O in p save p set 1 p save p set 2 get p 0 get p 1 get p 2 get p 3 get p 4 int list 2 1 0 0 0 3 15 Recursive classes Recursive classes can be used to define objects whose types are mutually recursive class window object val mutable top_widget None widget option method top_widget top_widget end and widget w window object val window w method window window H H HH H HOF OF end class window object val mutable top_widget widget option method top_widget widget option end and widget window gt object val window window method window window end Although their types are mutually recursive the classes widg
334. hods P p enable disable warnings for partial matches missing cases in pattern matchings S s enable disable warnings for statements that do not have type unit e g exprl expr2 when ezpr1 does not have type unit U u enable disable warnings for unused redundant match cases V v enable disable warnings for hidden instance variables X x enable disable all other warnings The default setting is w Al all warnings but labels enabled warn error warning list Turn the warnings indicated in the argument warning list into errors The compiler will stop on an error as soon as one of these warnings is emitted instead of going on The warning list is a string of one or several characters with the same meaning as for the w option an uppercase character turns the corresponding warning into an error a lowercase character leaves it as a warning The default setting is warn error a all warnings are not treated as errors where Print the location of the standard library Options for the IA32 architecture The IA32 code generator Intel Pentium AMD Athlon supports the following additional option ffast math Use the IA32 instructions to compute trigonometric and exponential functions instead of calling the corresponding library routines The functions affected are atan atan2 cos log log10 sin sqrt and tan The resulting code runs faster but the range of supported argu ments and the precision of the result can be redu
335. hrough floating point computations as expected for instance 1 0 infinity is 0 0 and any operation with nan as argument returns nan as result val float gt float 272 Unary negation You can also write e instead of e val float gt float gt float Floating point addition val float gt float gt float Floating point subtraction val float gt float gt float Floating point multiplication val float gt float gt float Floating point division val float gt float gt float Exponentiation val sqrt float gt float Square root val exp float gt float Exponential val log float gt float Natural logarithm val log10 float gt float Base 10 logarithm val cos float gt float See Pervasives atan2 19 2 val sin float gt float See Pervasives atan2 19 2 val tan float gt float See Pervasives atan2 19 2 val acos float gt float See Pervasives atan2 19 2 val asin float gt float See Pervasives atan2 19 2 Chapter 19 The core library 273 val val val val val val val val val val val val val val atan float gt float See Pervasives atan2 19 2 atan2 float gt float gt float The usual trigonometric functions cosh float gt float See Pervasives tanh sinh float gt float See Pervasives tanh tanh
336. ibraries 00 ih pu r whe day aw 5 gan N E Ay aa OA e s Se es BS Sh ats oe ees ce ee ee 21 The unix library Unix system calls 21 1 Module Unix Interface to the Unix system 220 4 21 2 Module UnixLabels labelized version of the interface 22 The num library arbitrary precision rational arithmetic 22 1 Module Num Operation on arbitrary precision numbers 285 287 289 293 294 295 295 297 298 299 311 316 317 320 323 326 327 329 333 335 337 340 341 342 342 344 346 348 352 355 355 356 360 361 364 367 371 371 404 23 The str library regular expressions and string processing 23 1 Module Str Regular expressions and high level string processing 24 The threads library 24 1 Module Thread Lightweight threads for Posix 1003 1c and Win32 24 2 Module Mutex Locks for mutual exclusion 0 00 00000004 24 3 Module Condition Condition variables to synchronize between threads 24 4 Module Event First class synchronous communication 24 5 Module ThreadUnix Thread compatible system calls 25 The graphics library Module Graphics Machine independent graphics primitives 26 The dbm library access to NDBM databases 26 1 Module Dbm Interface to the NDBM database 0 0 0 0000 4 27 The dynlink library dynamic loa
337. icates positions relative to the current position SEEK_END indicates positions relative to the end of the file Positioning modes for Unix 1seek 21 1 val lseek file_descr gt int gt seek_command gt int Set the current position for a file descriptor val truncate string gt int gt unit Truncates the named file to the given size val ftruncate file_descr gt int gt unit Truncates the file corresponding to the given descriptor to the given size File statistics type file_kind S_REG Regular file S_DIR Directory S_CHR Character device S_BLK Block device S_LNK Symbolic link S_FIFO Named pipe S_SOCK Socket type stats st_dev int Chapter 21 The unix library Unix system calls Device number st_ino int Inode number st_kind file_kind Kind of the file st_perm file_perm Access rights st_nlink int Number of links st_uid int User id of the owner st_gid int Group ID of the file s group st_rdev int Device minor number st_size int Size in bytes st_atime float Last access time st_mtime float Last modification time st_ctime float Last status change time The informations returned by the Unix stat calls val stat string gt stats Return the informations for the named file val lstat string gt stats 381 Same as Unix stat 21 1 but in case the file is a symbolic link return the informations
338. ides in the Objective Caml standard li brary directory and lists directory names one per line to be searched Typically it contains only one line naming the stublibs subdirectory of the Objective Caml standard library di rectory Users can add there the names of other directories containing frequently used shared libraries however for consistency of installation we recommend that shared libraries are installed directly in the system stublibs directory rather than adding lines to the 1d conf file 5 Default directories searched by the system dynamic loader Under Unix these generally include lib and usr 1ib plus the directories listed in the file etc ld so conf and the environment variable LD_LIBRARY_PATH Under Windows these include the Windows system directories plus the directories listed in the PATH environment variable 10 4 Common errors This section describes and explains the most frequently encountered error messages filename no such file or directory If filename is the name of a self executable bytecode file this means that either that file does not exist or that it failed to run the ocamlrun bytecode interpreter on itself The second possibility indicates that Objective Caml has not been properly installed on your system Cannot exec ocamlrun When launching a self executable bytecode file The ocamlrun could not be found in the executable path Check that Objective Caml has been properly installed on your system
339. ified with the o option man Generate documentation as a set of Unix man pages The generated pages are stored in the current directory or in the directory specified with the d option dot Generate a dependency graph for the toplevel modules in a format suitable for display ing and processing by dot The dot tool is available from The textual representation of the graph is written to the file ocamldoc out or to the file specified with the o option Use dot ocamldoc out to display it g file cm o a Dynamically load the given file which defines a custom documentation generator See section This option is supported by the ocamldoc command but not by its native code version ocamldoc opt If the given file is a simple one and does not exist in the current directory then ocamldoc looks for it in the custom generators default directory and in the directories specified with optional i options customdir Display the custom generators default directory i directory Add the given directory to the path where to look for custom generators General options d dir Generate files in directory dir rather than in the current directory dump file Dump collected information into file This information can be read with the load option in a subsequent invocation of ocamldoc hide modules Hide the given complete module names in the generated documentation modules is a list of complete module names are separated by witho
340. igarray library 467 Three dimensional arrays module Array3 sig type Ca b c t val The type of three dimensional big arrays whose elements have Caml type a representation kind b and memory layout c create a b Bigarray kind gt c Bigarray layout gt int gt int gt int gt a b c t val val val val val val val Array3 create kind layout dim1 dim2 dim3 returns a new bigarray of three dimension whose size is dim1 in the first dimension dim2 in the second dimension and dim3 in the third kind and layout determine the array element kind and the array layout as described for Bigarray Genarray create 29 1 dimi Ca b c t gt int Return the first dimension of the given three dimensional big array dim2 Ca b c t gt int Return the second dimension of the given three dimensional big array dim3 a b c t gt int Return the third dimension of the given three dimensional big array kind a b c t gt a b Bigarray kind Return the kind of the given big array layout a b c t gt c Bigarray layout Return the layout of the given big array get Ca b c t gt int gt int gt int gt a Array3 get a x y z also written a x y z returns the element of a at coordinates x y z x y and z must be within the bounds of a as described for Bigarray Genarray get 29 1 otherwise
341. ight versions of the shared libraries are found at start up time The second drawback of dynamic linking is that it complicates the construction of the library The C compiler and linker flags to compile to position independent code and build a shared library vary wildly between different Unix systems Also dynamic linking is not supported on all Unix systems requiring a fall back case to static linking in the Makefile for the library The ocamlmklib command see section tries to hide some of these system dependencies In conclusion dynamic linking is highly recommended under the native Windows port because there are no portability problems and it is much more convenient for the end users Under Unix dynamic linking should be considered for mature frequently used libraries because it enhances platform independence of bytecode executables For new or rarely used libraries static linking is much simpler to set up in a portable way Chapter 18 Interfacing C with Objective Caml 237 18 1 6 Building standalone custom runtime systems It is sometimes inconvenient to build a custom runtime system each time Caml code is linked with C libraries like ocamlc custom does For one thing the building of the runtime system is slow on some systems that have bad linkers or slow remote file systems for another thing the platform independence of bytecode files is lost forcing to perform one ocamlc custom link per platform of interest An alternative t
342. ignored if it starts with Thus it should be possible to make the script itself executable and put as first line usr local bin ocaml thus calling the toplevel system automatically when the script is run However ocam1 itself is a script on most installations of Objective Caml and Unix kernels usually do not handle nested scripts A better solution is to put the following as the first line of the script usr local bin ocamlrun usr local bin ocaml Chapter 9 The toplevel system ocaml 155 Windows In addition to the text only command ocaml exe which works exactly as under Unix see above a graphical user interface for the toplevel is available under the name ocamlwin exe It should be launched from the Windows file manager or program manager This interface provides a text window in which commands can be entered and edited and the toplevel responses are printed 9 1 Options The following command line options are recognized by the ocaml command I directory Add the given directory to the list of directories searched for source and compiled files By default the current directory is searched first then the standard library directory Directories added with I are searched after the current directory in the order in which they were given on the command line but before the standard library directory If the given directory starts with it is taken relative to the standard library directory For instance I labltk
343. ile that does not exist yet Fix compile mod m1 first If your program spans several directories this error can also appear because you haven t specified the directories to look into Fix add the correct I options to the command line Corrupted compiled interface filename The compiler produces this error when it tries to read a compiled interface file cmi file that has the wrong structure This means something went wrong when this cmi file was written the disk was full the compiler was interrupted in the middle of the file creation and so on This error can also appear if a cmi file is modified after its creation by the compiler Fix remove the corrupted cmi file and rebuild it This expression has type t but is used with type tz This is by far the most common type error in programs Type t is the type inferred for the expression the part of the program that is displayed in the error message by looking at the expression itself Type tz is the type expected by the context of the expression it is deduced by looking at how the value of this expression is used in the rest of the program If the two types t and t are not compatible then the error above is produced In some cases it is hard to understand why the two types t and t2 are incompatible For instance the compiler can report that expression of type foo cannot be used with type foo and it really seems that the two types foo are compatible This is not always t
344. incr_num index index_from 359 362 inet _addr 393 inet_addr_any 393 inet _addr_loopback inet_addr_of_string 393 inet6_addr_any 393 inet6_addr_loopback infinity init input input_binary_int 281 input_byte 8T input _char 28T input_line 28T input _value 282 int 205 B10 BT ET int_elt int_of_big_int 413 int_of_char int_of float int_of_nun int_of_string int16_signed int16_signed_elt int16_unsigned int16_unsigned_elt Int32 320 int 32 35 260 346 347 159 int32_elt 457 Int64 inva 155 PO B20 BIT E53 int64_elt int8_signed int8_signed_elt int8_unsigned int8_unsigned_elt integer_num inter 353 interactive 365 interval_timer 391 interval_timer_status 891 inv 296 invalid_arg 268 Invalid_argument is_empty is_implicit 298 is_int_big_int is_integer_num is_relative 298 iter 319 330 360 B62 870 41 iter2 iteri join junk key 288 B19 B34 key_pressed kfprintf x11 BEB PA INDEX TO THE LIBRARY kind 457 460 463 465 467 kprintf kscanf 852 ksprintf land LargeFile last_chars Layout 50 G0 f T H67 Lazy Lazy module lazy_from_fun lazy_from_val 326 lazy_is_val 826 lazy_t 2606 ldexp le_big_int le_num 1ength 230 293 B8 BTO E29 BH 950 B57 59 B01 B63 lexbuf lexeme lexeme_char lexeme_end lexeme_end_p 828 l
345. ine words used to store the given big integer Conversions to and from strings val string_of_big_int big_int gt string Return the string representation of the given big integer in decimal base 10 val big_int_of_string string gt big_int Convert a string to a big integer in decimal The string consists of an optional or sign followed by one or several decimal digits Conversions to and from other numerical types val big_int_of_int int gt big_int Convert a small integer to a big integer val is_int_big_int big_int gt bool Test whether the given big integer is small enough to be representable as a small integer type int without loss of precision On a 32 bit platform is_int_big_int a returns true if and only if a is between 2 and 229 1 On a 64 bit platform is_int_big_int a returns true if and only if a is between 262 and 262 1 val int_of_big_int big_int gt int Convert a big integer to a small integer type int Raises Failure int_of_big_int if the big integer is not representable as a small integer val float_of_big_int big_int gt float Returns a floating point number approximating the given big integer 414 22 3 Module Arith_status Flags that control rational arithmetic val val val val val val val val val val val arith_status unit gt unit Print the current status of the arithmetic flags get_error_when_null_denominator unit
346. ing list The argument is a string of one or several characters with the following meaning for each character A a enable disable all warnings C c enable disable warnings for suspicious comments D d enable disable warnings for deprecated features E e enable disable warnings for fragile pattern matchings matchings that would remain complete if additional constructors are added to a variant type involved F f enable disable warnings for partially applied functions i e f x expr where the appli cation f x has a function type L l enable disable warnings for labels omitted in application M m enable disable warnings for overriden methods P p enable disable warnings for partial matches missing cases in pattern matchings S s enable disable warnings for statements that do not have type unit e g exprl expr2 when ezpr1 does not have type unit U u enable disable warnings for unused redundant match cases V v enable disable warnings for hidden instance variables X x enable disable all other warnings The default setting is w Ael all warnings enabled except fragile matchings and omitted labels warn error warning list Turn the warnings indicated in the argument warning list into errors The compiler will stop Chapter 8 Batch compilation ocamlc 149 on an error as soon as one of these warnings is emitted instead of going on The warning list is a string of one or several characters with the same meaning as for the
347. ing of elements is involved the slice and the original array share the same storage space Genarray slice_left applies only to big arrays in C layout Raise Invalid_arg if M gt N orif Clit iM is outside the bounds of a slice_right a b Bigarray fortran_layout t gt int array gt a b Bigarray fortran_layout t val val Extract a sub array of lower dimension from the given big array by fixing one or several of the last right most coordinates Genarray slice_right a il iM returns the slice of a obtained by setting the last M coordinates to i1 iM If a has N dimensions the slice has dimension N M and the element at coordinates Clj1 j N M in the slice is identical to the element at coordinates j1 jJCN M it iM in the original array a No copying of elements is involved the slice and the original array share the same storage space Genarray slice_right applies only to big arrays in Fortran layout Raise Invalid_arg if M gt N or if li1 iMI is outside the bounds of a blit a b c t gt Ca b c t gt unit Copy all elements of a big array in another big array Genarray blit src dst copies all elements of src into dst Both arrays src and dst must have the same number of dimensions and equal dimensions Copying a sub array of src to a sub array of dst can be achieved by applying Genarray blit to sub array or slices of src a
348. inition is introduced by the keyword fun fun parameter parameter gt expr This expression is equivalent to fun parameter gt fun parameter gt expr Functions of the form fun optlabel pattern expry gt expr are equivalent to fun optlabel x gt let pattern match x with Some x gt x None gt expr in expr where x is a fresh variable When expr will be evaluated is left unspecified After these two transformations expressions are of the form fun label pattern gt fun label pattern gt expr If we ignore labels which will only be meaningful at function application this is equivalent to function pattern gt function pattern gt expr That is the fun expression above evaluates to a curried function with n arguments after applying this function n times to the values v Um the values will be matched in parallel against the patterns pattern pattern If the matching succeeds the function returns the value of expr in an environment enriched by the bindings performed during the matchings If the matching fails the exception Match_failure is raised Guards in pattern matchings Cases of a pattern matching in the function fun match and try constructs can include guard expressions which are arbitrary boolean expressions that must evaluate to true for the match case to be selected Guards occur just before the gt token and are introduced by the when keyword function pattern wh
349. inning returns the position of the first character of the substring that was matched by Str string_match 23 1 Str search_forward or Str search_backward match_end unit gt int match_end returns the position of the character following the last character of the substring that was matched by string_match search_forward or search_backward matched_group int gt string gt string matched_group n s returns the substring of s that was matched by the nth group of the regular expression during the latest Str string_match 23 1 Str search_forward or Str search_backward 23 1 The user must make sure that the parameter s is the same string that was passed to the matching or searching function matched_group n s raises Not_found if the nth group of the regular expression was not matched This can happen with groups inside alternatives options or repetitions For instance the empty string will match a but matched_group 1 will raise Not_found because the first group itself was not matched group_beginning int gt int group_beginning n returns the position of the first character of the substring that was matched by the nth group of the regular expression Raises e Not_found if the nth group of the regular expression was not matched e Invalid_argument if there are fewer than n groups in the regular expression group_end int gt int 418 group_end n returns the position of the character follo
350. int The native integer 1 val minus_one nativeint The native integer 1 val neg nativeint gt nativeint Unary negation val add nativeint gt nativeint gt nativeint Addition val sub nativeint gt nativeint gt nativeint Subtraction val mul nativeint gt nativeint gt nativeint Multiplication val div nativeint gt nativeint gt nativeint Integer division Raise Division_by_zero if the second argument is zero This division rounds the real quotient of its arguments towards zero as specified for Pervasives 19 2 val rem nativeint gt nativeint gt nativeint Integer remainder If y is not zero the result of Nativeint rem x y satisfies the following properties Nativeint zero lt Nativeint rem x y lt Nativeint abs y and x Nativeint add Nativeint mul Nativeint div x y y Nativeint rem x y Ify 0 Nativeint rem x y raises Division_by_zero val succ nativeint gt nativeint Successor Nativeint succ x is Nativeint add x Nativeint one val pred nativeint gt nativeint Predecessor Nativeint pred x is Nativeint sub x Nativeint one val abs nativeint gt nativeint Return the absolute value of its argument Chapter 20 The standard library 339 val val val val val val val val val val val val size int The size in bits of a native integer This is equal to 32 on a 32 bit platform and to 64 ona 64 bit pla
351. integer argument to unsigned hexadecimal using lowercase letters e X convert an integer argument to unsigned hexadecimal using uppercase letters e o convert an integer argument to unsigned octal e s insert a string argument Chapter 20 The standard library 343 Ww insert a string argument in Caml syntax double quotes escapes c insert a character argument C insert a character argument in Caml syntax single quotes escapes f convert a floating point argument to decimal notation in the style dddd ddd F convert a floating point argument in Caml syntax dddd ddd with a mandatory e or E convert a floating point argument to decimal notation in the style d ddd e dd mantissa and exponent g or G convert a floating point argument to decimal notation in style f or e E whichever is more compact B convert a boolean argument to the string true or false b convert a boolean argument for backward compatibility do not use in new programs ld li lu 1x 1X lo convert an int32 argument to the format specified by the second letter decimal hexadecimal etc nd ni nu nx nX no convert a nativeint argument to the format specified by the second letter Ld Li Lu Lx LX Lo convert an int64 argument to the format specified by the second letter a user defined printer Takes two arguments and apply the first one to outchan the current output channel and to the second argument The first argumen
352. interface cmi that combines the cmx object files given on the command line making them appear as sub modules of the output cmx file The name of the output cmx file must be given with the o option For instance ocamlopt pack o p cmx a cmx b cmx c cmx Chapter 11 Native code compilation ocamlopt 171 generates compiled files p cmx p o and p cmi describing a compilation unit having three sub modules A B and C corresponding to the contents of the object files a cmx b cmx and c cmx These contents can be referenced as P A P B and P C in the remainder of the program Unix The pack option is available only under platforms that provide the GNU Binutils tools nm and objcopy pp command Cause the compiler to call the given command as a preprocessor for each source file The output of command is redirected to an intermediate file which is compiled If there are no compilation errors the intermediate file is deleted afterwards The name of this file is built from the basename of the source file with the extension ppi for an interface m1i file and ppo for an implementation m1 file principal Check information path during type checking to make sure that all types are derived in a principal way All programs accepted in principal mode are also accepted in default mode with equivalent types but different binary signatures rectypes Allow arbitrary recursive types during type checking By default only recursive types
353. ion let f function A gt C B gt D val f A B DJ as a gt a f E DP Al BICI DI E E X gt X55 lt fun gt Here we are seeing two phenomena First since this matching is open the last case catches any tag we obtain the type gt A B rather than lt A B in a closed matching Then since x is returned as is input and return types are identical The notation as a denotes such type sharing If we apply f to yet another tag E it gets added to the list let f1 function A x gt x 1 B gt true C gt false let f2 function A x gt x a B gt true val f1 lt A of int B C gt bool lt fun gt val f2 lt A of string B gt bool lt fun gt let f x f1 x amp amp f2 x val f lt A of string amp int B gt bool lt fun gt Here f1 and f2 both accept the variant tags A and B but the argument of A is int for f1 and string for f2 In f s type C only accepted by f1 disappears but both argument types appear for Aas int amp string This means that if we pass the variant tag A to f its argument should be both int and string Since there is no such value f cannot be applied to A and B is the only accepted input Even if a value has a fixed variant type one can still give it a larger type through coercions Coer
354. ion 0 as usual search_forward regexp gt string gt int gt int search_forward r s start searches the string s for a substring matching the regular expression r The search starts at position start and proceeds towards the end of the string Return the position of the first character of the matched substring or raise Not_found if no substring matches Chapter 23 The str library regular expressions and string processing 417 val val val val val val val val search_backward regexp gt string gt int gt int search_backward r s last searches the string s for a substring matching the regular expression r The search first considers substrings that start at position last and proceeds towards the beginning of string Return the position of the first character of the matched substring raise Not_found if no substring matches string_partial_match regexp gt string gt int gt bool Similar to Str string_match 23 1 but succeeds whenever the argument string is a prefix of a string that matches This includes the case of a true complete match matched_string string gt string matched_string s returns the substring of s that was matched by the latest Str string_match 23 1 Str search_forward 23 1 or Str search_backward 23 1 The user must make sure that the parameter s is the same string that was passed to the matching or searching function match_beginning unit gt int match_beg
355. ion whose value is a floating point number High level network connection functions val open_connection sockaddr gt Pervasives in_channel Pervasives out_channel Connect to a server at the given address Return a pair of buffered channels connected to the server Remember to call Pervasives flush on the output channel at the right times to ensure correct synchronization val shutdown_connection Pervasives in_channel gt unit Shut down a connection established with Unix open_connection 21 1 that is transmit an end of file condition to the server reading on the other side of the connection val establish_server Pervasives in_channel gt Pervasives out_channel gt unit gt sockaddr gt unit Establish a server on the given address The function given as first argument is called for each connection with two buffered channels connected to the client A new process is created for each connection The function Unix establish_server never returns normally Host and protocol databases type host_entry h_name string h_aliases string array h_addrtype socket_domain h_addr_list inet_addr array Structure of entries in the hosts database type protocol_entry p_name string p_aliases string array p_proto int Chapter 21 The unix library Unix system calls Structure of entries in the protocols database type service_entry S_name string s_aliases string
356. ions type socket_bool_option SO_DEBUG Record debugging information SO_BROADCAST Permit sending of broadcast messages SO_REUSEADDR Allow reuse of local addresses for bind SO_KEEPALIVE Keep connection active SO_DONTROUTE Bypass the standard routing algorithms SO_OOBINLINE Leave out of band data in line SO_ACCEPTCONN Report whether socket listening is enabled The socket options that can be consulted with Unix getsockopt and modified with Unix setsockopt 21 1 These options have a boolean true false value type socket_int_option SO_SNDBUF Size of send buffer SO_RCVBUF Size of received buffer SO_ERROR Chapter 21 The unix library Unix system calls 397 Report the error status and clear it SO_TYPE Report the socket type SO_RCVLOWAT Minimum number of bytes to process for input operations SO_SNDLOWAT Minimum number of bytes to process for output operations The socket options that can be consulted with Unix getsockopt_int and modified with Unix setsockopt_int 21 1 These options have an integer value type socket_optint_option SO_LINGER Whether to linger on closed connections that have data present and for how long in seconds The socket options that can be consulted with Unix getsockopt_optint and modified with Unix setsockopt_optint 21 1 These options have a value of type int option with None meaning disabled type socket_float_option SO_RCVTI
357. ions apply in conjunction with the latex option Chapter 15 The documentation generator ocamldoc 199 latex value prefix prefix Give a prefix to use for the labels of the values in the generated TEX document The default prefix is the empty string You can also use the options latex type prefix latex exception prefix latex module prefix latex module type prefix latex class prefix latex class type prefix latex attribute prefix and latex method prefix These options are useful when you have for example a type and a value with the same name If you do not specify prefixes ATFX will complain about multiply defined labels latextitle n style Associate style number n to the given ATEX sectioning command style e g section or subsection IATpxX only This is useful when including the generated document in another TeX document at a given sectioning level The default association is 1 for section 2 for subsection 3 for subsubsection 4 for paragraph and 5 for subparagraph noheader Suppress header in generated documentation notoc Do not generate a table of contents notrailer Suppress trailer in generated documentation sepfiles Generate one tex file per toplevel module instead of the global ocamldoc out file Options for generating TeXinfo files The following options apply in conjunction with the texi option esc8 Escape accented characters in Info files info entry Specify Info directory entr
358. ipal mode Accessing and modifying instance variables The instance variables of a class are visible only in the body of the methods defined in the same class or a class that inherits from the class defining the instance variables The expression inst var name evaluates to the value of the given instance variable The expression inst var name lt expr assigns the value of expr to the instance variable inst var name which must be mutable The whole expression inst var name lt expr evaluates to Coercion The type of an object can be coerced weakened to a supertype The expression expr gt typexpr coerces the expression expr to type typexpr The expression expr typexpr gt typexpr coerces the expression expr from type typexpr to type typexprs The former operator will sometimes fail to coerce an expression expr from a type t to a type t2 even if type t is a subtype of type t2 in the current implementation it only expands two levels of type abbreviations containing objects and or variants keeping only recursion when it is explicit in the class type In case of failure the latter operator should be used In a class definition coercion to the type this class defines is the identity as this type abbrevi ation is not yet completely defined Object duplication An object can be duplicated using the library function 0o copy see section 20 21 Inside a method the expression lt inst var name expr inst var na
359. irs 1 That is assoc a a b bif a b is the leftmost binding of a in list 1 Raise Not_found if there is no value associated with a in the list 1 val assq a gt a b list gt b Same as List assoc 20 17 but uses physical equality instead of structural equality to compare keys val mem_assoc a gt a b list gt bool Same as List assoc 20 17 but simply return true if a binding exists and false if no bindings exist for the given key val mem_assq a gt a b list gt bool Same as List mem_assoc 20 17 but uses physical equality instead of structural equality to compare keys val remove_assoc a gt a b list gt a b list remove_assoc a 1 returns the list of pairs 1 without the first pair with key a if any Not tail recursive val remove_assq a gt a b list gt a b list Same as List remove_assoc 20 17 but uses physical equality instead of structural equality to compare keys Not tail recursive Lists of pairs val split a b list gt a list b list Transform a list of pairs into a pair of lists split ai b1 an bn is Lal an b1 bn Not tail recursive val combine a list gt b list gt a b list Transform a pair of lists into a list of pairs combine al an b1 bn is a1 b1 an bn Raise Invalid_argument if the two lis
360. ise Invalid_arg if n is less than 0 or greater or equal than Genarray num_dims a kind a b c t gt a b Bigarray kind Return the kind of the given big array layout a b c t gt c Bigarray layout Return the layout of the given big array et Ca b c t gt int array gt a g y Read an element of a generic big array Genarray get a li1 iNI returns the element of a whose coordinates are i1 in the first dimension i2 in the second dimension iN in the N th dimension If a has C layout the coordinates must be greater or equal than 0 and strictly less than the corresponding dimensions of a If a has Fortran layout the coordinates must be greater or equal than 1 and less or equal than the corresponding dimensions of a Raise Invalid_arg if the array a does not have exactly N dimensions or if the coordinates are outside the array bounds If N gt 3 alternate syntax is provided you can write a i1 i2 iN instead of Genarray get a il iN The syntax a with one two or three coordinates is reserved for accessing one two and three dimensional arrays as described below set Ca b c t gt int array gt a gt unit y Assign an element of a generic big array Genarray set a li1 iNI v stores the value v in the element of a whose coordinates are i1 in the first dimension i2 in the second dimension iN in the N th dimension C
361. ist UnixLabels write file_descr gt buf string gt pos int gt len int gt unit When there are several objects of same nature and role they are all left unlabeled ListLabels iter2 f a gt b gt c gt a list gt b list gt unit When there is no preferable object all arguments are labeled StringLabels blit src string gt src_pos int gt dst string gt dst_pos int gt len int gt unit However when there is only one argument it is often left unlabeled StringLabels create int gt string This principle also applies to functions of several arguments whose return type is a type variable as long as the role of each argument is not ambiguous Labeling such functions may lead to awkward error messages when one attempts to omit labels in an application as we have seen with ListLabels fold_left Here are some of the label names you will find throughout the libraries Label Meaning f a function to be applied pos a position in a string or array len a length buf a string used as buffer src the source of an operation dst the destination of an operation init the initial value for an iterator cmp a comparison function e g Pervasives compare mode an operation mode or a flag list All these are only suggestions but one shall keep in mind that the choice of labels is essential for readability Bizarre choices will make the program harder to maintain
362. it a format4 gt b Same as fprintf above but instead of returning immediately passes the formatter to its first argument at the end of printing val ksprintf string gt a gt b unit string a format4 gt b Same as sprintf above but instead of returning the string passes it to the first argument val kprintf string gt a gt b unit string a format4 gt b A deprecated synonym for ksprintf 20 10 Module Gc Memory management control and statistics finalised values type stat minor_words float Number of words allocated in the minor heap since the program was started This number is accurate in byte code programs but only an approximation in programs compiled to native code promoted_words float Number of words allocated in the minor heap that survived a minor collection and were moved to the major heap since the program was started major_words float Number of words allocated in the major heap including the promoted words since the program was started 312 minor_collections int Number of minor collections since the program was started major_collections int Number of major collection cycles completed since the program was started heap_words int Total size of the major heap in words heap_chunks int Number of contiguous pieces of memory that make up the major heap live_words int Number of words of li
363. it dup2 fdi fd2 duplicates fd1 to fd2 closing fd2 if already opened val set_nonblock file_descr gt unit Set the non blocking flag on the given descriptor When the non blocking flag is set reading on a descriptor on which there is temporarily no data available raises the EAGAIN or EWOULDBLOCK error instead of blocking writing on a descriptor on which there is temporarily no room for writing also raises EAGAIN or EWOULDBLOCK val clear_nonblock file_descr gt unit Clear the non blocking flag on the given descriptor See Unix set_nonblock val set_close_on_exec file_descr gt unit Set the close on exec flag on the given descriptor A descriptor with the close on exec flag is automatically closed when the current process starts another program with one of the exec functions val clear_close_on_exec file_descr gt unit Clear the close on exec flag on the given descriptor See Unix set_close_on_exec 21 1 Chapter 21 The unix library Unix system calls Directories val mkdir string gt file_perm gt unit Create a directory with the given permissions val rmdir string gt unit Remove an empty directory val chdir string gt unit Change the process working directory val getcwd unit gt string Return the name of the current working directory val chroot string gt unit Change the process root directory type dir_handle The type of descriptors over
364. it is empty Note that even if Weak check ar n returns true a subsequent Weak get 20 35 ar n can return None fill a t gt int gt int gt a option gt unit Weak fill ar ofs len el sets to el all pointers of ar from ofs to ofs len 1 Raise Invalid_argument Weak fill if ofs and len do not designate a valid subarray of a val blit a t gt int gt a t gt int gt int gt unit Weak blit ari off1 ar2 off2 len copies len weak pointers from ar1 starting at off1 to ar2 starting at of f2 It works correctly even if ar1 and ar2 are the same Raise Invalid_argument Weak blit if off1 and len do not designate a valid subarray of ar1 or if of f2 and len do not designate a valid subarray of ar2 Chapter 20 The standard library 369 Weak hash tables A weak hash table is a hashed set of values Each value may magically disappear from the set when it is not used by the rest of the program any more This is normally used to share data structures without inducing memory leaks Weak hash tables are defined on values from a Hashtbl HashedType 20 12 module the equal relation and hash function are taken from that module We will say that v is an instance of x if equal x v is true The equal relation must be able to work on a shallow copy of the values and give the same result as with the values themselves module type S sig type data The type of the elements stored in the table type t The type of tab
365. it is found If a closing bracket appears in a range it must occur as the first character of the range or just after the in case of range negation hence matches a character and matches any character that is not 1 applies f to the number of lines read so far n applies f to the number of characters read so far N applies f to the number of tokens read so far matches the end of input condition zs matches one character in the input Following the character introducing a conversion there may be the special flag _ the conversion that follows occurs as usual but the resulting value is discarded The field widths are composed of an optional integer literal indicating the maximal width of the token to read For instance 6d reads an integer having at most 6 decimal digits and 4f reads a float with at most 4 characters Chapter 20 The standard library 351 Scanning indications appear just after the string conversions s and range to delimit the end of the token A scanning indication is introduced by a character followed by some constant character c It means that the string token should end just before the next matching c which is skipped If no c character is encountered the string token spreads as much as possible For instance s t reads a string up to the next tabulation character If a scanning indication c does not follow a string conversion it is ignored and treated as a plain c charac
366. ith Caml code we now review the pros and cons of each to help developers of mixed Caml C libraries decide The main advantage of dynamic linking is that it preserves the platform independence of byte code executables That is the bytecode executable contains no machine code and can therefore be compiled on platform A and executed on other platforms B C as long as the required shared libraries are available on all these platforms In contrast executables generated by ocamlc custom run only on the platform on which they were created because they embark a custom tailored runtime system specific to that platform In addition dynamic linking results in smaller executables Another advantage of dynamic linking is that the final users of the library do not need to have a C compiler C linker and C runtime libraries installed on their machines This is no big deal under Unix and Cygwin but many Windows users are reluctant to install Microsoft Visual C just to be able to do ocamlc custom There are two drawbacks to dynamic linking The first is that the resulting executable is not stand alone it requires the shared libraries as well as ocamlrun to be installed on the machine executing the code If you wish to distribute a stand alone executable it is better to link it statically using ocamlc custom ccopt static or ocamlopt ccopt static Dynamic linking also raises the DLL hell problem some care must be taken to ensure that the r
367. ition 1 Size 3 unit QO Part II The Objective Caml language Chapter 6 The Objective Caml language Foreword This document is intended as a reference manual for the Objective Caml language It lists the language constructs and gives their precise syntax and informal semantics It is by no means a tutorial introduction to the language there is not a single example A good working knowledge of Caml is assumed No attempt has been made at mathematical rigor words are employed with their intuitive meaning without further definition As a consequence the typing rules have been left out by lack of the mathematical framework required to express them while they are definitely part of a full formal definition of the language Notations The syntax of the language is given in BNF like notation Terminal symbols are set in typewriter font like this Non terminal symbols are set in italic font like that Square brackets denote optional components Curly brackets denotes zero one or several repetitions of the enclosed components Curly bracket with a trailing plus sign denote one or several repetitions of the enclosed components Parentheses denote grouping 6 1 Lexical conventions Blanks The following characters are considered as blanks space newline horizontal tabulation carriage return line feed and form feed Blanks are ignored but they separate adjacent identifiers literals and keywor
368. ject create it without going through a class The syntax is exactly the same as for class expressions but the result is a single object rather than aclass All the constructs described in the rest of this section also apply to immediate objects let p object val mutable x 0 method get_x x method move d x lt x d end val p lt get_x int move int gt unit gt lt obj gt p get_x int 0 p move 3 unit p get_x int 3 Unlike classes which cannot be defined inside an expression immediate objects can appear anywhere using variables from their environment let minmax x y if x lt y then object method min x method max y end else object method min y method max x end val minmax a gt a gt lt max a min a gt lt fun gt Immediate objects have two weaknesses compared to classes their types are not abbreviated and you cannot inherit from them But these two weaknesses can be advantages in some situations as we will see in sections and 3 3 Reference to self A method or an initializer can send messages to self that is the current object For that self must be explicitly bound here to the variable s s could be any identifier even though we will often choose the name self Chapter 3 Objects in Caml 37 class printable_point x_init object s val mutable x x_init method get_x x
369. key gt a gt b gt b gt a t gt b gt b fold f m a computes f kN dN f ki di a where k1 KN are the keys of all bindings in m in increasing order and d1 dN are the associated data val compare a gt a gt int gt a t gt at gt int Total ordering between maps The first argument is a total ordering used to compare data associated with equal keys in the two maps val equal a gt a gt bool gt a t gt a t gt bool equal cmp m1 m2 tests whether the maps m1 and m2 are equal that is contain equal keys and associate them with equal data cmp is the equality predicate used to compare the data associated with the keys end Output signature of the functor Map Make 20 18 module Make functor Ord OrderedType gt S with type key Ord t Functor building an implementation of the map structure given a totally ordered type 20 19 Module Marshal Marshaling of data structures This module provides functions to encode arbitrary data structures as sequences of bytes which can then be written on a file or sent over a pipe or network connection The bytes can then be read back later possibly in another process and decoded back into a data structure The format for the byte sequences is compatible across all machines for a given version of Objective Caml Warning marshaling is currently not type safe The type of marshaled data is
370. key gt a gt b gt b gt a t gt b gt b val length a t gt int end The output signature of the functor Hashtbl Make 20 12 module Make functor H HashedType gt S with type key H t 319 Functor building an implementation of the hashtable structure The functor Hashtbl Make returns a structure containing a type key of keys and a type a t of hash tables associating data of type a to keys of type key The operations perform similarly to those of the generic interface but use the hashing and equality functions specified in the functor argument H instead of generic equality and hashing The polymorphic hash primitive val hash a gt int Hashtbl hash x associates a positive integer to any value of any type It is guaranteed that y or Pervasives compare x y 0 then hash x hash y Moreover hash always terminates even on cyclic structures if x 320 val hash_param Hashtbl hash_param n m x computes a hash value for x with the same properties as for hash The two extra parameters n and m give more precise control over hashing Hashing performs a depth first right to left traversal of the structure x stopping after n meaningful nodes were encountered or m nodes meaningful or not were encountered Meaningful nodes are integers floating point numbers strings characters booleans and constant constructors Larger values of m and n means that more nodes are
371. l exists f a gt bool gt a list gt bool for_all2 f a gt b gt bool gt a list gt b list gt bool exists2 f a gt b gt bool gt a list gt b list gt bool mem a gt set a list gt bool memq a gt set a list gt bool find f a gt bool gt a list gt a filter f a gt bool gt a list gt a list find_all f a gt bool gt a list gt a list partition f a gt bool gt a list gt a list a list assoc a gt a b list gt b assq a gt a b list gt b mem_assoc a gt map a b list gt bool mem_assq a gt map a b list gt bool remove_assoc a gt a b list gt a b list remove_assq a gt a b list gt a b list split a b list gt a list b list combine a list gt b list gt a b list sort cmp a gt a gt int gt a list gt a list stable_sort cmp a gt a gt int gt a list gt a list fast_sort cmp a gt a gt int gt a list gt a list merge cmp a gt a gt int gt a list gt a list gt a list Chapter 20 The standard library 359 end module String sig val val val val val val val val val length string
372. l as the variables BYTECCLINKOPTS for object files produced by ocamlc output obj and NATIVECCLINKOPTS for object files produced by ocamlopt output obj Currently the only ports that require special attention are e Alpha under Digital Unix Tru64 Unix with gcc object files produced by ocamlc output obj must be linked with the gcc options W1 T 12000000 W1 D 14000000 This is not necessary for object files produced by ocamlopt output obj e Windows NT the object file produced by Objective Caml have been compiled with the MT flag and therefore all other object files linked with it should also be compiled with MT 18 8 Advanced example with callbacks This section illustrates the callback facilities described in section 18 7 We are going to package some Caml functions in such a way that they can be linked with C code and called from C just like any C functions The Caml functions are defined in the following mod m1 Caml source useful Caml functions File mod ml some let rec fib n if n lt 2 then 1 else fib n 1 fib n 2 let format_result n Printf sprintf Result is d n n Export those two functions to C let _ Callback register fib fib let Callback register format_result format_result Here is the C stub code for calling these functions from C File modwrap c wrappers around the Caml functions include lt stdio h gt include lt string h gt include lt caml mlvalues h gt
373. l amount Although the initial implementation did not address this requirement it can be achieved by using an initializer class account_with_deposit x object inherit account_with_history initializer balance lt x end class account_with_deposit Euro c gt object val mutable balance Euro c 76 val mutable history Euro c operation list method balance Euro c method deposit Euro c gt unit method history Euro c operation list method private trace Euro c operation gt unit method withdraw Euro c gt Euro c end A better alternative is class account_with_deposit x object self inherit account_with_history initializer self deposit x end class account_with_deposit Euro c gt object val mutable balance Euro c val mutable history Euro c operation list method balance Euro c method deposit Euro c gt unit method history Euro c operation list method private trace Euro c operation gt unit method withdraw Euro c gt Euro c end Indeed the latter is safer since the call to deposit will automatically benefit from safety checks and from the trace Let s test it let ccp new account_with_deposit euro 100 in let balance ccp withdraw euro 50 in ccp history Euro c operation list Deposit lt obj gt Retrieval lt obj gt Closing an account can be done with the following polymorphic function let close c c wi
374. l be reduced if the precedence of the token is higher then the token will be shifted e A shift reduce conflict between a rule and a token with the same precedence will be resolved using the associativity if the token is left associative then the parser will reduce if the token is right associative then the parser will shift If the token is non associative then the parser will declare a syntax error e When ashift reduce conflict cannot be resolved using the above method then ocamlyacc will output a warning and the parser will always shift 182 12 4 3 Rules The syntax for rules is as usual nonterminal symbol symbol semantic action ere symbol symbol semantic action Rules can also contain the prec symbol directive in the right hand side part to override the default precedence and associativity of the rule with the precedence and associativity of the given symbol Semantic actions are arbitrary Caml expressions that are evaluated to produce the semantic attribute attached to the defined nonterminal The semantic actions can access the semantic attributes of the symbols in the right hand side of the rule with the notation 1 is the attribute for the first leftmost symbol 2 is the attribute for the second symbol etc The rules may contain the special symbol error to indicate resynchronization points as in yacc Actions occurring in the middle of rules are not supported Nonterminal symbols are like
375. l inv t gt t Multiplicative inverse 1 z val div t gt t gt t Division val sqrt t gt t Square root The result x i y is such that x gt O or x 0 and y gt 0 This function has a discontinuity along the negative real axis val norm2 t gt float Norm squared given x i y returns x 2 y 2 val norm t gt float Norm given x i y returns sqrt x 2 y 2 val arg t gt float Chapter 20 The standard library 297 Argument The argument of a complex number is the angle in the complex plane between the positive real axis and a line passing through zero and the number This angle ranges from pi to pi This function has a discontinuity along the negative real axis val polar float gt float gt t polar norm arg returns the complex having norm norm and argument arg val exp t gt t Exponentiation exp z returns e to the z power val log t gt t Natural logarithm in base e val pow t gt t gt t Power function pow z1 z2 returns z1 to the z2 power 20 7 Module Digest MD5 message digest This module provides functions to compute 128 bit digests of arbitrary length strings or files The digests are of cryptographic quality it is very hard given a digest to forge a string having that digest The algorithm used is MD5 type t string The type of digests 16 character strings val string string gt t Return the digest of the given string
376. l language 103 6 6 Patterns pattern value name constant pattern as value name pattern pattern typexpr pattern pattern constr pattern tag name pattern typeconstr name pattern pattern field pattern field pattern pattern pattern pattern pattern pattern pattern The table below shows the relative precedences and associativity of operators and non closed pattern constructions The constructions with higher precedences come first Operator Associativity Constructor application a right left as Patterns are templates that allow selecting data structures of a given shape and binding iden tifiers to components of the data structure This selection operation is called pattern matching its outcome is either this value does not match this pattern or this value matches this pattern resulting in the following bindings of names to values Variable patterns A pattern that consists in a value name matches any value binding the name to the value The pattern _ also matches any value but does not bind any name Patterns are linear a variable cannot appear several times in a given pattern In particular there is no way to test for equality between two parts of a data structure using only a pattern but when guards can be used for this purpose Constant patterns A pattern consisting in a constant matches the values that are e
377. l possible tags are also potentially present In all three cases tags may be either specified directly in the tag name form or indirectly through a type expression In this last case the type expression must expand to an exact variant type whose tag specifications are inserted in its place Full specification of variant tags are only used for non exact closed types They can be under stood as a conjunctive type for the argument it is intended to have all the types enumerated in the specification Such conjunctive constraints may be unsatisfiable In such a case the corresponding tag may not be used in a value of this type This does not mean that the whole type is not valid one can still use other available tags Object types An object type lt method type method type gt is a record of method types Each method may have an explicit polymorphic type ident typexpr Explicit poly morphic variables have a local scope and an explicit polymorphic type can only be unified to an equivalent one with polymorphic variables at the same positions The type lt method type method type gt is the type of an object with methods and their associated types are described by method type method type and possibly some other methods represented by the ellipsis This ellipsis actually is a special kind of type variable also called row variable in the literature that stands for any number of extra method types 10
378. l_printer printer name This directive registers the function named printer name a value path as a printer for values whose types match the argument type of the function That is the toplevel loop will call printer name when it has such a value to print Chapter 9 The toplevel system ocaml 157 The printing function printer name should have type Format formatter gt t gt unit where tis the type for the values to be printed and should output its textual representation for the value of type ton the given formatter using the functions provided by the Format library For backward compatibility printer name can also have type t gt unit and should then output on the standard formatter but this usage is deprecated remove_printer printer name Remove the named function from the table of toplevel printers trace function name After executing this directive all calls to the function named function name will be traced That is the argument and the result are displayed for each call as well as the exceptions escaping out of the function raised either by the function itself or by another function it calls If the function is curried each argument is printed as it is passed to the function untrace function name Stop tracing the given function untrace_all Stop tracing all functions traced so far print_depth n Limit the printing of values to a maximal depth of n The parts of values whose depth exceeds
379. lare the given symbols as tokens terminal symbols These symbols are added as constant constructors for the token concrete type token lt type gt symbol symbol Declare the given symbols as tokens with an attached attribute of the given type These symbols are added as constructors with arguments of the given type for the token concrete type The type part is an arbitrary Caml type expression except that all type constructor names must be fully qualified e g Modname typename for all types except standard built in types even if the proper open directives e g open Modname were given in the header section That s because the header is copied only to the m1 output file but not to the mli output file while the type part of a token declaration is copied to both Chapter 12 Lexer and parser generators ocamllex ocamlyacc 181 start symbol symbol Declare the given symbols as entry points for the grammar For each entry point a parsing function with the same name is defined in the output module Non terminals that are not declared as entry points have no such parsing function Start symbols must be given a type with the type directive below dAtype lt type gt symbol symbol Specify the type of the semantic attributes for the given symbols This is mandatory for start symbols only Other nonterminal symbols need not be given types by hand these types will be inferred when running the output files through the Objective Caml
380. lation ocamlopt 167 Egra a e my de a Bw Go ea leh Ge es ee a 167 ble gob Gh aE eee Gy Sar he pose ae Gala DE A Ge a See Re ee a 168 11 3 Common errors a aoaaa a 173 11 4 Running executables produced by ocamlopt 2 02585 173 Soca a aes Gs te e Gye es pene E Severe 173 175 Sean a aoa See a ORTE Oe ai p e BG R D a 175 eBoy aia ag p e ae aT Rw ew e Se le ee a 176 e phe E S aye Ge e a e a al oe e a yes 179 e ee ee te ee oe ee 180 A bugh BS OO PE ee Fa we Eee a eR Re Ae oe eee ed 182 Bg 0 eaae aea a be Ee eG ce ek 183 12 7 Commo errors s ae Rw SGA BER eA Saw eG he we Bee he Be ed 184 13 Dependency generator ocamldep 187 a eee Boos ae ate we ar Yh oy oe aa N ya Geek cess Gs eae Saha Gt es aye 187 Eo ae Rae Roe op gt ar ew eee Gey Ae er ee SS Gs Myint Ge ee ae 188 14 The browser editor ocamlbrowser 191 Pk gh HE a Eek Ree Suk ekg Wb ok Gee os Be el Ge a 191 14 2 Viewen o ge WB Oe BR Oe Se ea 192 14 3 Module browsing s cs sa sacs oa dane aa a aaa ee 192 IAA File editor eaga eae a a a Aaa ae a g ak a a a A aR S 193 145 Shell s zore a eae a y k a d we ER e e ep e e ee es ES 193 15 The documentation generator ocamldoc 195 dee Bowe See ea ee a et See ee pe es es See a gs ete ee ee 195 rae ete ee ee aes eg Ge ee Ge ee ere ee 201 hha He Eia amp ae doy Hae Eee ae ek oR Erk eg 210 eh posh Grd FE E Wee Gra oe en ee 6 212 16 The debugger ocamldebug 215 16 1 Compiling for debugging oaoa a a ee 215 a deren se
381. lback_exn callback2_exn callback3_exn callbackN_exn These functions take the same arguments as their non _exn counterparts but catch escaping exceptions and return them to the C code The return value v of the callback _exn functions must be tested with the macro Is_exception_result v If the macro returns false no exception occured and v is the value returned by the Caml function If Is_exception_result v returns true an exception escaped and its value the exception descriptor can be recovered using Extract_exception v 18 7 2 Registering Caml closures for use in C functions The main difficulty with the callback functions described above is obtaining a closure to the Caml function to be called For this purpose Objective Caml provides a simple registration mechanism by which Caml code can register Caml functions under some global name and then C code can retrieve the corresponding closure by this global name On the Caml side registration is performed by evaluating Callback register n v Here n is the global name an arbitrary string and v the Caml value For instance let f x print_string f is applied to print_int n print_newline let _ Callback register test function f On the C side a pointer to the value registered under name n is obtained by calling caml_named_value n The returned pointer must then be dereferenced to recover the actual Caml value If no value is registered under the name n the null
382. lection and compact the heap Note that heap compaction is a lengthy operation print_stat Pervasives out_channel gt unit Print the current values of the memory management counters in human readable form into the channel argument allocated_bytes unit gt float Return the total number of bytes allocated since the program was started It is returned as a float to avoid overflow problems with int on 32 bit machines finalise a gt unit gt a gt unit Chapter 20 The standard library 315 finalise f v registers f as a finalisation function for v v must be heap allocated f will be called with v as argument at some point between the first time v becomes unreachable and the time v is collected by the GC Several functions can be registered for the same value or even several instances of the same function Each instance will be called once or never if the program terminates before v becomes unreachable The GC will call the finalisation functions in the order of deallocation When several values become unreachable at the same time i e during the same GC cycle the finalisation functions will be called in the reverse order of the corresponding calls to finalise If finalise is called in the same order as the values are allocated that means each value is finalised before the values it depends upon Of course this becomes false if additional dependencies are introduced by assignments Anything reachable from th
383. lent to print_tbreak 0 0 304 Ellipsis val set_ellipsis_text string gt unit Set the text of the ellipsis printed when too many boxes are opened a single dot by default val get_ellipsis_text unit gt string Return the text of the ellipsis Tags type tag string Tags are used to decorate printed entities for user s defined purposes e g setting font and giving size indications for a display device or marking delimitations of semantics entities e g HTML or TeX elements or terminal escape sequences By default those tags do not influence line breaking calculation the tag markers are not considered as part of the printing material that drives line breaking in other words the length of those strings is considered as zero for line breaking Thus tag handling is in some sense transparent to pretty printing and does not interfere with usual pretty printing Hence a single pretty printing routine can output both simple verbatim material or richer decorated output depending on the treatment of tags By default tags are not active hence the output is not decorated with tag information Once set_tags is set to true the pretty printer engine honors tags and decorates the output accordingly When a tag has been opened or closed it is both and successively printed and marked Printing a tag means calling a formatter specific function with the name of the tag as argument that tag prin
384. leq that expects an argument of type money since it accesses its value method Considering m of type comparable would allow to call method leq on m with an argument that does not have a method value which would be an error Similarly the type money2 below is not a subtype of type money class money2 x object inherit money x method times k lt repr k repr gt end class money2 float gt object a val repr float Chapter 3 Objects in Caml 59 method leq a gt bool method times float gt a method value float end It is however possible to define functions that manipulate objects of type either money or money2 the function min will return the minimum of any two objects whose type unifies with comparable The type of min is not the same as comparable gt comparable gt comparable as the abbreviation comparable hides a type variable an ellipsis Each occurrence of this abbreviation generates a new variable let min x comparable y if x leq y then x else y val min comparable as a gt a gt a lt fun gt This function can be applied to objects of type money or money2 min new money 1 3 new money 3 1 value float 1 3 min new money2 5 0 new money2 3 14 value float 3 14 More examples of binary methods can be found in sections and 5 2 3 Notice the use of functional update for method times Writing new
385. les Either you have forgotten to provide an implementation for the compilation unit named mod on the command line typically the file named mod cmo or a library containing that file Fix add the missing ml or cmo file to the command line Or you have provided an implementation for the module named mod but it comes too late on the command line the implementation of mod must come before all bytecode object files that reference mod Fix change the order of ml and cmo files on the command line Of course you will always encounter this error if you have mutually recursive functions across modules That is function Mod1 f calls function Mod2 g and function Mod2 g calls function Modi f In this case no matter what permutations you perform on the command line the program will be rejected at link time Fixes e Put f and g in the same module e Parameterize one function by the other That is instead of having modi ml let f x Mod2 g mod2 m1 let gy Modi f define modi ml Let f g F sia Gos mod2 m1 let rec g y Modi fg and link mod1 cmo before mod2 cmo 152 e Use a reference to hold one of the two functions as in modi ml let forward_g ref fun x gt failwith forward_g lt type gt let f x forward_g mod2 m1 let gy Mod1 f let _ Modi forward_g g The external function fis not available This error appears when trying to link code that calls external functions written in
386. les that contain elements of type data Note that weak hash tables cannot be marshaled using Pervasives output_value or the functions of the Marshal 20 19 module val create int gt t create n creates a new empty weak hash table of initial size n The table will grow as needed val clear t gt unit Remove all elements from the table val merge t gt data gt data merge t x returns an instance of x found in t if any or else adds x to t and return x val add t gt data gt unit add t x adds x tot If there is already an instance of x in t it is unspecified which one will be returned by subsequent calls to find and merge val remove t gt data gt unit remove t x removes from t one instance of x Does nothing if there is no instance of x in t val find t gt data gt data find t x returns an instance of x found in t Raise Not_found if there is no such element val find_all t gt data gt data list 370 val val val val val end find_all t x returns a list of all the instances of x found in t mem t gt data gt bool mem t x returns true if there is at least one instance of x in t false otherwise iter data gt unit gt t gt unit iter f t calls f on each element of t in some unspecified order It is not specified what happens if f tries to change t itself fold data gt a gt a gt t gt a gt a fold f t init
387. let construct described above is that the bindings of names to values performed by the pattern matching are considered already performed when the expressions expr to expr are evaluated That is the expressions expr to expr can reference identifiers that are bound by one of the patterns pattern pattern and expect them to have the same value as in expr the body of the let rec construct The recursive definition is guaranteed to behave as described above if the expressions expr to expr are function definitions fun or function and the patterns pattern pattern are just value names as in n let rec name fun and and name fun in expr This defines name namen as mutually recursive functions local to expr The behavior of other forms of let rec definitions is implementation dependent The current implementation also supports a certain class of recursive definitions of non functional values as explained in section 6 7 2 Control structures Sequence The expression expr expr evaluates expr first then exprs and returns the value of exprs 112 Conditional The expression if expr then expr else exprs evaluates to the value of expr if expr evaluates to the boolean true and to the value of expr if expr evaluates to the boolean false The else expr part can be omitted in which case it defaults to else Case expression The expression match expr with pattern gt expr patte
388. lias for the type of native integers val compare t gt t gt int The comparison function for native integers with the same specification as Pervasives compare Along with the type t this function compare allows the module Nativeint to be passed as argument to the functors Set Make 20 28 and Map Make 20 18 20 21 Module 0o Operations on objects val copy lt gt as a gt a Oo copy o returns a copy of object o that is a fresh object with the same methods and instance variables as o val id lt gt gt int Return an integer identifying this object unique for the current execution of the program Chapter 20 The standard library 341 20 22 Module Parsing The run time library for parsers gener val val val val val val val val val ated by ocamlyacc symbol_start unit gt int symbol_start and Parsing symbol_end 20 22 are to be called in the action part of a grammar rule only They return the offset of the string that matches the left hand side of the rule symbol_start returns the offset of the first character symbol_end returns the offset after the last character The first character in a file is at offset 0 symbol_end unit gt int See Parsing symbol_start 20 22 rhs_start int gt int Same as Parsing symbol_start 20 22 and Parsing symbol_end 20 22 but return the offset of the string matching the nth item on the right hand side of the r
389. libraries given on the command line This custom runtime system can be used later to execute bytecode executables produced with the ocamlc use runtime runtime name option See section 18 1 6 for more information noassert Turn assertion checking off assertions are not compiled This flag has no effect when linking already compiled files noautolink When linking cma libraries ignore custom cclib and ccopt options potentially con tained in the libraries if these options were given when building the libraries This can be useful if a library contains incorrect specifications of C libraries or C options in this case during linking set noautolink and pass the correct C libraries and options on the command line nolabels Ignore non optional labels in types Labels cannot be used in applications and parameter order becomes strict Chapter 8 Batch compilation ocamlc 147 o exec file Specify the name of the output file produced by the linker The default output name is a out in keeping with the Unix tradition If the a option is given specify the name of the library produced If the output obj option is given specify the name of the output file produced output obj Cause the linker to produce a C object file instead of a bytecode executable file This is useful to wrap Caml code as a C library callable from any C program See chapter 18 section 18 7 5 The name of the output object file is camlprog o by default it c
390. licitly allocated and deallocated from memory all memory management is entirely automatic in Caml Similarly there is no explicit handling of pointers the Caml compiler silently introduces pointers where necessary As with most Caml data structures inspecting and destructuring lists is performed by pattern matching List patterns have the exact same shape as list expressions with identifier representing unspecified parts of the list As an example here is insertion sort on a list let rec sort lst match lst with 0 gt O head tail gt insert head sort tail and insert elt lst match lst with gt elt head tail gt if elt lt head then elt lst else head insert elt tail HHHH H HF OF Chapter 1 The core language 13 re val sort a list gt a list lt fun gt val insert a gt a list gt a list lt fun gt sort 1 string list a etc is tale told The type inferred for sort a list gt a list means that sort can actually apply to lists of any type and returns a list of the same type The type a is a type variable and stands for any given type The reason why sort can apply to lists of any type is that the comparisons lt etc are polymorphic in Caml they operate between any two values of the same type This makes sort itself polymorphic over all list types sort 6 2 5 3 int list 2 3 5 6 sort 3 14 2 71
391. lid_argument s where s is a null terminated C string with type char raises ex ception Invalid_argument with argument s Raising arbitrary exceptions from C is more delicate the exception identifier is dynamically allocated by the Caml program and therefore must be communicated to the C function using the registration facility described below in section Once the exception identifier is recovered in C the following functions actually raise the exception raise_constant id raises the exception id with no argument raise_with_arg id v raises the exception id with the Caml value v as argument raise_with_string id s where s is a null terminated C string raises the exception id with a copy of the C string s as argument 18 5 Living in harmony with the garbage collector Unused blocks in the heap are automatically reclaimed by the garbage collector This requires some cooperation from C code that manipulates heap allocated blocks 18 5 1 Simple interface All the macros described in this section are declared in the memory h header file 244 Rule 1 A function that has parameters or local variables of type value must begin with a call to one of the CAMLparam macros and return with CAMLreturn or CAMLreturn0 There are six CAMLparam macros CAMLparamO to CAMLparam5 which take zero to five arguments respectively If your function has fewer than 5 parameters of type value use the corresponding macros with these parameters as argu
392. ll meta characters 20 9 Module Format Pretty printing This module implements a pretty printing facility to format text within pretty printing boxes The pretty printer breaks lines at specified break hints and indents lines according to the box structure For a gentle introduction to the basics of prety printing using Format read the FAQ at http caml inria fr FAQ format eng html Warning the material output by the following functions is delayed in the pretty printer queue in order to compute the proper line breaking Hence you should not mix calls to the printing functions of the basic I O system with calls to the functions of this module this could result in some strange output seemingly unrelated with the evaluation order of printing commands You may consider this module as providing an extension to the printf facility to provide au tomatic line breaking The addition of pretty printing annotations to your regular printf formats gives you fancy indentation and line breaks Pretty printing annotations are described below in the documentation of the function Format fprintf 20 9 300 You may also use the explicit box management and printing functions provided by this module This style is more basic but more verbose than the fprintf concise formats For instance the sequence open_box 0 print_string x print_space print_int 1 close_box that prints x 1 within a pretty printing box can be abbreviated as printf
393. lling init all compilation units composing the program currently running are available for reference from dynamically linked units allow_only can be used to grant access to some of them only e g to the units that compose the API for dynamically linked code and prevent access to all other units e g private internal modules of the running program val prohibit string list gt unit prohibit units prohibits dynamically linked units from referencing the units named in list units This can be used to prevent access to selected units e g private internal modules of the running program val default_available_units unit gt unit Reset the set of units that can be referenced from dynamically linked code to its default value that is all units composing the currently running program val allow_unsafe_modules bool gt unit Govern whether unsafe object files are allowed to be dynamically linked A compilation unit is unsafe if it contains declarations of external functions which can break type safety By default dynamic linking of unsafe object files is not allowed Deprecated low level API for access control val add_interfaces string list gt string list gt unit add_interfaces units path grants dynamically linked object files access to the compilation units named in list units The interfaces cmi files for these units are searched in path a list of directory names val add_available_units string Dig
394. location between the assignment where it takes its value and the modify statement that uses the value 18 6 A complete example This section outlines how the functions from the Unix curses library can be made available to Objective Caml programs First of all here is the interface curses mli that declares the curses primitives and data types type window The type window remains abstract external initscr unit gt window curses_initscr external endwin unit gt unit curses_endwin external refresh unit gt unit curses_refresh external wrefresh window gt unit curses_wrefresh external newwin int gt int gt int gt int gt window curses_newwin 248 external mvwin window gt int gt int gt unit curses_mvwin external addch char gt unit curses_addch external mvwaddch window gt int gt int gt char gt unit curses_mvwaddch external addstr string gt unit curses_addstr external mvwaddstr window gt int gt int gt string gt unit curses_mvwaddstr lots more omitted To compile this interface ocamlc c curses mli To implement these functions we just have to provide the stub code the core functions are already implemented in the curses library The stub code file curses o looks like include lt curses h gt include lt mlvalues h gt value curses_initscr value unit CAMLparam1 unit CAMLreturn value initscr
395. lock_8 Write an array of 8 byte quantities deserialize_uint_1 Read an unsigned 1 byte integer deserialize_sint_1 Read a signed 1 byte integer deserialize_uint_2 Read an unsigned 2 byte integer deserialize_sint_2 Read a signed 2 byte integer deserialize_uint_4 Read an unsigned 4 byte integer deserialize_sint_4 Read a signed 4 byte integer deserialize_uint_8 Read an unsigned 8 byte integer deserialize_sint_8 Read a signed 8 byte integer deserialize_float_4 Read a 4 byte float deserialize_float_8 Read an 8 byte float deserialize_block_1 Read an array of 1 byte quantities deserialize_block_2 Read an array of 2 byte quantities deserialize_block_4 Read an array of 4 byte quantities deserialize_block_8 Read an array of 8 byte quantities deserialize_error Signal an error during deserialization input_value or Marshal from_ raise a Failure exception after cleaning up their internal data structures Serialization functions are attached to the custom blocks to which they apply Obviously dese rialization functions cannot be attached this way since the custom block does not exist yet when deserialization begins Thus the struct custom_operations that contain deserialization functions must be registered with the deserializer in advance using the register_custom_operations func tion declared in lt caml custom h gt Deserialization proceeds by reading the identifier off the input stream allocating a
396. lopt The source code must be put in a file with extension m1 It consists of a sequence of phrases which will be evaluated at runtime in their order of appearance in the source file Unlike in interactive mode types and values are not printed automatically the program must call printing functions explicitly to produce some output Here is a sample standalone program to print Fibonacci numbers File fib ml let rec fib n if n lt 2 then 1 else fib n 1 fib n 2 let main let arg int_of_string Sys argv 1 in print_int fib arg print_newline exit 0 main Sys argv is an array of strings containing the command line parameters Sys argv 1 is thus the first command line parameter The program above is compiled and executed with the following shell commands ocamlc o fib fib ml fib 10 89 fib 20 10946 24 Chapter 2 The module system This chapter introduces the module system of Objective Caml 2 1 Structures A primary motivation for modules is to package together related definitions such as the definitions of a data type and associated operations over that type and enforce a consistent naming scheme for these definitions This avoids running out of names or accidentally confusing names Such a package is called a structure and is introduced by the struct end construct which contains an arbitrary sequence of definitions The structure is usually given a name with the module binding
397. lows e The reason for the error unknown option invalid or missing argument etc e usage_msg e The list of options each followed by the corresponding doc string For the user to be able to specify anonymous arguments starting with a include for example String anon_fun doc in speclist By default parse recognizes two unit options help and help which will display usage_msg and the list of options and exit the program You can override this behaviour by specifying your own help and help options in speclist Chapter 20 The standard library 289 val parse_argv current int Pervasives ref gt string array gt key spec doc list gt anon_fun gt usage_msg gt unit Arg parse_argv current args speclist anon_fun usage_msg parses the array args as if it were the command line It uses and updates the value of current if given or Arg current You must set it before calling parse_argv The initial value of current is the index of the program name argument 0 in the array If an error occurs Arg parse_argv raises Arg Bad with the error message as argument If option help or help is given Arg parse_argv raises Arg Help with the help message as argument exception Help of string Raised by Arg parse_argv when the user asks for help exception Bad of string Functions in spec or anon_fun can raise Arg Bad with an error message to reject invalid arguments Arg Bad is also raised by Arg parse_arg
398. ly slower programs The default is to optimize for speed dtypes Dump detailed type information The information for file z m1l is put into file z annot In case of a type error dump all the information inferred by the type checker before the error The z annot file can be used with the emacs commands given in emacs caml types el to display types interactively Cause the compiler to print all defined names with their inferred types or their definitions when compiling an implementation m1 file No compiled files cmo and cmi files are produced This can be useful to check the types inferred by the compiler Also since the output follows the syntax of interfaces it can help in writing an explicit interface m1i file for a file just redirect the standard output of the compiler to a mli file and edit that file to remove all declarations of unexported names I directory Add the given directory to the list of directories searched for compiled interface files cmi compiled object code files cmx and libraries cmxa By default the current directory is searched first then the standard library directory Directories added with I are searched after the current directory in the order in which they were given on the command line but before the standard library directory If the given directory starts with it is taken relative to the standard library directory For instance I labltk adds the subdirectory labltk of the sta
399. ly used buffer This happens in particular when calling fscanf again after a scan involving a format that necessitates some look ahead such as a format that ends by skipping whitespace in the input To avoid confusion consider using bscanf with an explicitly created scanning buffer Use for instance Scanning from_file f to allocate the scanning buffer reading from file f This method is not only clearer it is also faster since scanning buffers to files are optimized for fast bufferized reading val sscanf string gt a Scanning scanbuf b Pervasives format gt a gt b Same as Scanf bscanf 20 27 but inputs from the given string 302 val scanf a Scanning scanbuf b Pervasives format gt a gt b Same as Scanf bscanf 20 27 but reads from the predefined scanning buffer Scanf Scanning stdib 20 27 that is connected to stdin val kscanf Scanning scanbuf gt Scanning scanbuf gt exn gt a gt Cb Scanning scanbuf a Pervasives format gt b gt a Same as Scanf bscanf 20 27 but takes an additional function argument ef that is called in case of error if the scanning process or some conversion fails the scanning function aborts and applies the error handling function ef to the scanning buffer and the exception that aborted the scanning process 20 28 Module Set Sets over ordered types This module implements the set data structure given a total ordering fu
400. mation of the space used by the buffer 294 val add_char t gt char gt unit add_char b c appends the character c at the end of the buffer b val add_string t gt string gt unit add_string b s appends the string s at the end of the buffer b val add_substring t gt string gt int gt int gt unit add_substring b s ofs len takes len characters from offset ofs in string s and appends them at the end of the buffer b val add_substitute t gt string gt string gt string gt unit add_substitute b f s appends the string pattern s at the end of the buffer b with substitution The substitution process looks for variables into the pattern and substitutes each variable name by its value as obtained by applying the mapping f to the variable name Inside the string pattern a variable name immediately follows a non escaped character and is one of the following e anon empty sequence of alphanumeric or _ characters e an arbitrary sequence of characters enclosed by a pair of matching parentheses or curly brackets An escaped character is a that immediately follows a backslash character it then stands for a plain Raise Not_found if the closing character of a parenthesized variable cannot be found val add_buffer t gt t gt unit add_buffer b1 b2 appends the current contents of buffer b2 at the end of buffer b1 b2 is not modified val add_channel t gt Pervasives in_channel gt in
401. me expr gt returns a copy of self with the given instance variables replaced by the values of the associated expressions other instance variables have the same value in the returned object as in self Chapter 6 The Objective Caml language 117 6 8 Type and exception definitions 6 8 1 Type definitions Type definitions bind type constructors to data types either variant types record types type abbreviations or abstract data types They also bind the value constructors and record fields associated with the definition type definition type typedef and typedef typedef type params typeconstr name type information type information type equation type representation type constraint type equation typexpr type representation constr decl constr decl field decl field decl type params type param type param type param type param ident ident ident constr decl constr name constr name of typexpr field decl field name poly typexpr mutable field name poly typexpr type constraint constraint ident typexpr Type definitions are introduced by the type keyword and consist in one or several simple definitions possibly mutually recursive separated by the and keyword Each simple definition defines one type constructor A simple definition consists in a lowercase identifier possibly preceded by one or several type parameters and follow
402. ment a value of type typexpr and return as result a class of type class type Class body type The class type expression object typexpr class field spec end is the type of a class body It specifies its instance variables and methods In this type typexpr is matched against the self type therefore providing a binding for the self type A class body will match a class body type if it provides definitions for all the components specified in the class type and these definitions meet the type requirements given in the class type Furthermore all methods either virtual or public present in the class body must also be present in the class type on the other hand some instance variables and concrete private methods may be omitted A virtual method will match a concrete method which makes it possible to forget its implementation An immutable instance variable will match a mutable instance variable Inheritance The inheritance construct inherit class type allows to include methods and instance variables from other classes types The instance variable and method types from this class type are added into the current class type Chapter 6 The Objective Caml language 121 Instance variable specification A specification of an instance variable is written val mutable inst var name typexpr where inst var name is the name of the instance variable and typexpr its expected type The flag mutable indicates whether this instance variable can
403. ment to have it match the expected type by passing None for all optional parameters let twice f x int f f x val twice int gt int gt int gt int lt fun gt twice bump 2 int 8 This transformation is coherent with the intended semantics including side effects That is if the application of optional parameters shall produce side effects these are delayed until the received function is really applied to an argument 4 1 3 Suggestions for labeling Like for names choosing labels for functions is not an easy task A good labeling is a labeling which e makes programs more readable e is easy to remember e when possible allows useful partial applications We explain here the rules we applied when labeling Objective Caml libraries To speak in an object oriented way one can consider that each function has a main argument its object and other arguments related with its action the parameters To permit the combination 68 of functions through functionals in commuting label mode the object will not be labeled Its role is clear by the function itself The parameters are labeled with names reminding either of their nature or role Best labels combine in their meaning nature and role When this is not possible the role is to prefer since the nature will often be given by the type itself Obscure abbreviations should be avoided ListLabels map f a gt b gt a list gt b l
404. ments If your function has more than 5 parameters of type value use CAMLparam5 with five of these parameters and use one or more calls to the CAMLxparam macros for the remaining parameters CAMLxparam1 to CAMLxparam5 The macros CAMLreturn and CAMLreturn0 are used to replace the C keyword return Every occurence of return x must be replaced by CAMLreturn x every occurence of return without argument must be replaced by CAMLreturnO If your C function is a procedure i e if it returns void you must insert CAMLreturn0 at the end to replace C s implicit return Note some C compilers give bogus warnings about unused variables cam1__dummy_xxx at each use of CAMLparam and CAMLlocal You should ignore them Example void foo value vi value v2 value v3 CAMLparam3 v1 v2 v3 CAMLreturn0O Note if your function is a primitive with more than 5 arguments for use with the byte code runtime its arguments are not values and must not be declared they have types value and int Rule 2 Local variables of type value must be declared with one of the CAMLlocal macros Arrays of values are declared with CAMLlocalN The macros CAMLlocali to CAMLlocal5 declare and initialize one to five local variables of type value The variable names are given as arguments to the macros CAMLlocalN z n declares and initializes a local variable of type value n You can use several calls to these macros if you have more than 5 local variables Y
405. mes are capitalized to distinguish them from variable names which must start with a lowercase letter For instance here is a variant type for doing mixed arithmetic integers and floats type number Int of int Float of float Error type number Int of int Float of float Error This declaration expresses that a value of type number is either an integer a floating point number or the constant Error representing the result of an invalid operation e g a division by zero Enumerated types are a special case of variant types where all alternatives are constants type sign Positive Negative type sign Positive Negative let sign_int n if n gt 0 then Positive else Negative val sign_int int gt sign lt fun gt To define arithmetic operations for the number type we use pattern matching on the two num bers involved Chapter 1 The core language 15 let add_num ni n2 match ni n2 with Int i1 Int i2 gt Check for overflow of integer addition if sign_int i1 sign_int i2 amp amp sign_int il i2 lt gt sign_int il then Float float i1 float i2 else Int i1 i2 Int i1 Float f2 gt Float float i1 f2 Float f1 Int i2 gt Float f1 float i2 Float f1 Float f2 gt Float f1 f2 Error _ gt Error _ Error gt Error val add_num number gt number gt number lt fun gt add_num Int 123
406. method move d x lt x d method print print_int s get_x end class printable_point int gt object val mutable x int method get_x int method move int gt unit method print unit end let p new printable_point 7 val p printable_point lt obj gt p print 7 unit Dynamically the variable s is bound at the invocation of a method In particular when the class printable_point is inherited the variable s will be correctly bound to the object of the subclass A common problem with self is that as its type may be extended in subclasses you cannot fix it in advance Here is a simple example let ints ref val ints _a list ref contents class my_int object self method n 1 method register ints self ints end This expression has type lt n int register a gt but is here used with type b Self type cannot escape its class You can ignore the first two lines of the error message What matters is the last one putting self into an external reference would make it impossible to extend it afterwards We will see in section 3 12 a workaround to this problem Note however that since immediate objects are not extensible the problem does not occur with them let my_int object self method n 1 method register ints self ints end val my_int lt n int register unit gt lt obj gt 38
407. mg in place The pixels copied are those inside the rectangle with lower left corner at x y and width and height equal to those of the image Pixels that were transparent in img are left unchanged Mouse and keyboard events type status mouse_x int X coordinate of the mouse mouse_y int Y coordinate of the mouse button bool true if a mouse button is pressed keypressed bool true if a key has been pressed key char the character for the key pressed To report events type event Button_down A mouse button is pressed Button_up 436 A mouse button is released Key_pressed A key is pressed Mouse_motion The mouse is moved Poll Don t wait return immediately To specify events to wait for val wait_next_event event list gt status Wait until one of the events specified in the given event list occurs and return the status of the mouse and keyboard at that time If Poll is given in the event list return immediately with the current status If the mouse cursor is outside of the graphics window the mouse_x and mouse_y fields of the event are outside the range 0 size_x 1 0 size_y 1 Keypresses are queued and dequeued one by one when the Key_pressed event is specified Mouse and keyboard polling val mouse_pos unit gt int int Return the position of the mouse cursor relative to the graphics window If the mouse cursor is outside of the graphics window mous
408. mic linking of C libraries is supported on your platform start ocaml and type load dbm cma Windows This library is not available 26 1 Module Dbm Interface to the NDBM database type t The type of file descriptors opened on NDBM databases 439 440 type open_flag Dbm_rdonly Dbm_wronly Dbm_rdwr Dbm_create Flags for opening a database see Dom opendbm 26 1 exception Dbm_error of string val val val val val val val val Raised by the following functions when an error is encountered opendbm string gt open_flag list gt int gt t Open a descriptor on an NDBM database The first argument is the name of the database without the dir and pag suffixes The second argument is a list of flags Dbm_rdonly opens the database for reading only Dbm_wronly for writing only Dbm_rdwr for reading and writing Dbm_create causes the database to be created if it does not already exist The third argument is the permissions to give to the database files if the database is created close t gt unit Close the given descriptor find t gt string gt string find db key returns the data associated with the given key in the database opened for the descriptor db Raise Not_found if the key has no associated data add t gt string gt string gt unit add db key data inserts the pair key data in the database db If the database already contains data associated with k
409. mitted type flush_queue TCIFLUSH TCOFLUSH TCIOFLUSH val tcflush file_descr gt flush_queue gt unit Discard data written on the given file descriptor but not yet transmitted or data received but not yet read depending on the second argument TCIFLUSH flushes data received but not read TCOFLUSH flushes data written but not transmitted and TCIOFLUSH flushes both type flow_action TCOOFF TCOON TCIOFF TCION val tcflow file_descr gt flow_action gt unit Suspend or restart reception or transmission of data on the given file descriptor depending on the second argument TCOOFF suspends output TCOON restarts output TCIOFF transmits a STOP character to suspend input and TCION transmits a START character to restart input val setsid unit gt int Put the calling process in a new session and detach it from its controlling terminal 21 2 Module UnixLabels labelized version of the interface This module is identical to Unix 21 1 and only differs by the addition of labels You may see these labels directly by looking at unixLabels mli or by using the ocamlbrowser tool Chapter 21 The unix library Unix system calls 405 Windows The Cygwin port of Objective Caml fully implements all functions from the Unix module The native Win32 ports implement a subset of them Below is a list of the functions that are not implemented or only partially implemented by the Win32 ports Functions not mentioned ar
410. mming environments This chapter assumes a working knowledge of lex and yacc while it describes the input syntax for ocamllex and ocamlyacc and the main differences with lex and yacc it does not explain the basics of writing a lexer or parser description in lex and yacc Readers unfamiliar with lex and yacc are referred to Compilers principles techniques and tools by Aho Sethi and Ullman Addison Wesley 1986 or Lex amp Yacc by Levine Mason and Brown O Reilly 1992 12 1 Overview of ocamllex The ocamllex command produces a lexical analyzer from a set of regular expressions with attached semantic actions in the style of lex Assuming the input file is lerer m11 executing ocamllex lerer m11 produces Caml code for a lexical analyzer in file lerer m1 This file defines one lexing function per entry point in the lexer definition These functions have the same names as the entry points Lexing functions take as argument a lexer buffer and return the semantic attribute of the corresponding entry point Lexer buffers are an abstract data type implemented in the standard library module Lexing The functions Lexing from_channel Lexing from_string and Lexing from_function create lexer buffers that read from an input channel a character string or any reading function respec tively See the description of module Lexing in chapter 20 When used in conjunction with a parser generated by ocamlyacc the semantic actions comput
411. module to ensure that construc tion of values of the private type always go through the functions provided by the module while still allowing pattern matching outside the defining module For example module M sig type t private A B of int vala t val b int gt t end struct type t A B of int let a A let b n assert n gt 0 Bn end Here the private declaration ensures that in any value of type M t the argument to the B con structor is always a positive integer 7 9 Recursive modules definition module rec module name module type module expr and module name module type module expr specification module rec module name module type and module name module type Recursive module definitions introduced by the module rec and construction gen eralize regular module definitions module module name module expr and module specifications module module name module type by allowing the defining module expr and the module type to refer recursively to the module identifiers being defined A typical example of a recursive module definition is module rec A sig type t Leaf of string Node of ASet t val compare t gt t gt int end struct type t Leaf of string Node of ASet t let compare t1 t2 match t1 t2 with Leaf s1 Leaf s2 gt Pervasives compare s1 s2 Leaf _ Node _ gt 1 Chapter 7 Language extensions 139 Node _ Leaf _ g
412. n 6 9 3 Class type definitions A definition of one or several classes is written class type classtype def and classtype def and consists of a sequence of mutually recursive definitions of class type names Class type definitions are described more precisely in section 6 9 5 Module definitions The basic form for defining a module component is module module name module expr which evaluates module expr and binds the result to the name module name One can write module module name module type module expr instead of module module name module expr module type Another derived form is module module name name module type name module type module expr which is equivalent to module module name functor name module type gt gt module expr 132 Module type definitions A definition for a module type is written module type modtype name module type It binds the name modtype name to the module type denoted by the expression module type Opening a module path The expression open module path in a structure does not define any components nor perform any bindings It simply affects the parsing of the following items of the structure allowing components of the module denoted by module path to be referred to by their simple names name instead of path accesses module path name The scope of the open stops at the end of the structure expression Including the components of another structure
413. n though they can appear in any order The order in which expr to expr are evaluated is not specified The expression expr with field expr field expr builds a fresh record with fields field field equal to expr expr and all other fields having the same value as in the record expr In other terms it returns a shallow copy of the record expr except for the fields field field which are initialized to expr expr The expression expr field evaluates expr to a record value and returns the value associated to field in this record value The expression expr field lt expry evaluates expr to a record value which is then modified in place by replacing the value associated to field in this record by the value of expry This operation is permitted only if field has been declared mutable in the definition of the record type The whole expression expr field lt expr evaluates to the unit value Arrays The expression expr expr evaluates to a n element array whose elements are ini tialized with the values of expr to expr respectively The order in which these expressions are evaluated is unspecified The expression expr expr returns the value of element number expr in the array denoted by expr The first element has number 0 the last element has number n 1 where n is the size of the array The exception Invalid_argument is raised if the access is out of bounds
414. n x c0 gt x cO gt c1 c0 gt c1 lt fun gt However the domain of the coercion cannot be omitted here fun x c0 gt x gt c1 This expression cannot be coerced to type c1 lt m cl gt it has type cO lt m c0 n int gt but is here used with type lt m cl as a gt Type c0 lt m c0 n int gt is not compatible with type a lt m cl gt Type c0 lt m c0 n int gt is not compatible with type cl lt m c1 gt Only the first object type has a method n This simple coercion was not fully general Consider using a double coercion The solution is to use the explicit form Sometimes a change in the class type definition can also solve the problem class type c2 object a method m a end class type c2 object a method m a end fun x c0 gt x gt c2 c0 gt c2 lt fun gt While class types c1 and c2 are different both object types c1 and c2 expand to the same object type same method names and types Yet when the domain of a coercion is left implicit and its co domain is an abbreviation of a known class type then the class type rather than the object type is used to derive the coercion function This allows to leave the domain implicit in most cases when coercing form a subclass to its superclass The type of a coercion can always be seen as below let to_c1 x x gt c1 val to_c1 lt m c1 gt gt c
415. n be made public in a subclass class point_again x object self inherit restricted_point x method virtual move end class point_again int gt object val mutable x int method bump unit method get_x int method move int gt unit end The annotation virtual here is only used to mention a method without providing its definition Since we didn t add the private annotation this makes the method public keeping the original definition An alternative definition is class point_again x object self lt move _ gt inherit restricted_point x end class point_again int gt object val mutable x int method bump unit method get_x int method move int gt unit end The constraint on self s type is requiring a public move method and this is sufficient to override private One could think that a private method should remain private in a subclass However since the method is visible in a subclass it is always possible to pick its code and define a method of the same name that runs that code so yet another heavier solution would be class point_again x object inherit restricted_point x as super method move super move Chapter 3 Objects in Caml 41 end class point_again int gt object val mutable x int method bump unit method get_x int method move int gt unit end Of course private methods can also be virtual Then
416. n bytes of the data part of the custom block This size must be identical to the wsize_32 result of the serialize operation if the architecture is 32 bits or wsize_64 if the architecture is 64 bits The deserialize field can be set to custom_deserialize_default to indicate that deseri alization is not supported In this case do not register the struct custom_operations with the deserializer using register_custom_operations see below 18 9 2 Allocating custom blocks Custom blocks must be allocated via the alloc_custom function alloc_custom ops size used max returns a fresh custom block with room for size bytes of user data and whose associated operations are given by ops a pointer to a struct custom_operations usually statically allocated as a C global variable The two parameters used and maz are used to control the speed of garbage collection when the finalized object contains pointers to out of heap resources Generally speaking the Caml incre mental major collector adjusts its speed relative to the allocation rate of the program The faster the program allocates the harder the GC works in order to reclaim quickly unreachable blocks and avoid having large amount of floating garbage unreferenced objects that the GC has not yet collected Normally the allocation rate is measured by counting the in heap size of allocated blocks However it often happens that finalized objects contain pointers to out of heap memory blocks a
417. n directories to the search path These directories are added at the front and will therefore be searched first directory Reset the search path This requires confirmation 16 8 4 Working directory Each time a program is started in the debugger it inherits its working directory from the current working directory of the debugger This working directory is initially whatever it inherited from its parent process typically the shell but you can specify a new working directory in the debugger with the cd command or the cd command line option cd directory Set the working directory for camldebug to directory pwd Print the working directory for camldebug 16 8 5 Turning reverse execution on and off In some cases you may want to turn reverse execution off This speeds up the program execution and is also sometimes useful for interactive programs Normally the debugger takes checkpoints of the program state from time to time That is it makes a copy of the current state of the program using the Unix system call fork If the variable checkpoints is set to off the debugger will not take any checkpoints set checkpoints on off Select whether the debugger makes checkpoints or not 16 8 6 Communication between the debugger and the program The debugger communicate with the program being debugged through a Unix socket You may need to change the socket name for example if you need to run the debugger on a machine and your program on
418. n element in the result of the functor and t in its argument is forgotten Consequently WrongStringSet element is not the same type as string and the operations of WrongStringSet cannot be applied to strings As demonstrated above it is important that the type element in the signature SET be declared equal to Elt t unfortunately this is impossible above since SET is defined in a context where Elt does not exist To overcome this difficulty Objective Caml provides a with type construct over signatures that allows to enrich a signature with extra type equalities module AbstractSet Set functor Elt ORDERED_TYPE gt SET with type element Elt t module AbstractSet functor Elt ORDERED_TYPE gt sig type element Elt t type set val empty set val add element gt set gt set Chapter 2 The module system 31 val member element gt set gt bool end As in the case of simple structures an alternate syntax is provided for defining functors and restricting their result module AbstractSet Elt ORDERED_TYPE SET with type element Elt t struct end Abstracting a type component in a functor result is a powerful technique that provides a high degree of type safety as we now illustrate Consider an ordering over character strings that is different from the standard ordering implemented in the OrderedString structure For instance we compare strings without distinguishing upper and lower case
419. n order to satisfy the GC constraints alloc_tuple n returns a fresh block of size n words with tag 0 alloc_string n returns a string value of length n characters The string initially contains garbage copy_string s returns a string value containing a copy of the null terminated C string s a char copy_double d returns a floating point value initialized with the double d copy_int32 7 copy_int64 7 and copy_nativeint i return a value of Caml type int32 int64 and nativeint respectively initialized with the integer i alloc_array f a allocates an array of values calling function f over each element of the input array a to transform it into a value The array a is an array of pointers terminated by the null pointer The function f receives each pointer as argument and returns a value The zero tagged block returned by alloc_array f a is filled with the values returned by the successive calls to f This function must not be used to build an array of floating point numbers copy_string_array p allocates an array of strings copied from the pointer to a string array p a char p must be NULL terminated Low level interface The following functions are slightly more efficient than alloc but also much more difficult to use From the standpoint of the allocation functions blocks are divided according to their size as zero sized blocks small blocks with size less than or equal to Max_young_wosize and large block
420. n units unit interface specification unit implementation definition Compilation units bridge the module system and the separate compilation system A compila tion unit is composed of two parts an interface and an implementation The interface contains a sequence of specifications just as the inside of a sig end signature expression The implemen tation contains a sequence of definitions just as the inside of a struct end module expression A compilation unit also has a name unit name derived from the names of the files containing the interface and the implementation see chapter 8 for more details A compilation unit behaves roughly as the module definition module unit name sig unit interface end struct unit implementation end A compilation unit can refer to other compilation units by their names as if they were regular modules For instance if U is a compilation unit that defines a type t other compilation units can refer to that type under the name U t they can also refer to U as a whole structure Except for names of other compilation units a unit interface or unit implementation must not have any other free variables In other terms the type checking and compilation of an interface or implementation proceeds in the initial environment name sig interface end name sig interface end where name namen are the names of the other compilation units available in the search path see cha
421. nal argument in an option type let test2 x y test x y O Q val test2 x int gt y int gt unit gt int int int lt fun gt test2 x None y int gt unit gt int int int lt fun gt 4 1 2 Labels and type inference While they provide an increased comfort for writing function applications labels and optional arguments have the pitfall that they cannot be inferred as completely as the rest of the language You can see it in the following two examples let h g g y 2 x 3 val h y int gt x int gt a gt a lt fun gt hb 3 This expression has type x int gt y int gt int but is here used with type y int gt x int gt a let bump_it bump x bump step 2 x val bump_it step int gt a gt b gt a gt b lt fun gt bump_it bump 1 This expression has type step int gt int gt int but is here used with type step int gt a gt b The first case is simple g is passed y and then x but f expects x and then y This is correctly handled if we know the type of g to be x int gt y int gt int in advance but otherwise this causes the above type clash The simplest workaround is to apply formal parameters in a standard order The second example is more subtle while we intended the argument bump to be of type step int gt int gt int it is inferred as step int gt int gt a The
422. nce variable is ignored At last is the empty documentation comment 15 2 4 Text formatting Here is the BNF grammar for the simple markup language used to format text descriptions 208 tert text_element text_element 0 9 text format text as a section header the integer following indi cates the sectioning level 0 9 label text same but also associate the name label to the current point This point can be referenced by its fully qualified label in a command just like any other element b teat set text in bold i text set text in italic e text emphasize text C text center tert L text left align text R text right align text ul list build a list ol list build an enumerated list string text put a link to the given address given as a string on the given text string set the given string in source code style Lstring set the given string in preformatted source code style v string v set the given string in verbatim style string take the given string as raw IATRX code string insert a reference to the element named string string must be a fully qualified element name for example Foo Bar t The kind of the referenced element can be forced use ful when various elements have the same qualified name with the following syntax kind Foo Bar t where kind can be module modtype class classtype val type
423. nction The following must be true for all x y z in a e cmp x y gt 0 if and only if cmp y x lt 0 e if cmp x y gt 0 and cmp y z gt 0 then cmp x z gt 0 When Array sort returns a contains the same elements as before reordered in such a way that for all i and j valid indices of a e cmp a i a j gt 0 if and only ifi gt j val stable_sort a gt a gt int gt a array gt unit Same as Array sort 20 2 but the sorting algorithm is stable i e elements that compare equal are kept in their original order and not guaranteed to run in constant heap space The current implementation uses Merge Sort It uses n 2 words of heap space where n is the length of the array It is usually faster than the current implementation of Array sort 20 2 Chapter 20 The standard library 293 val fast_sort a gt a gt int gt a array gt unit Same as Array sort or Array stable_sort whichever is faster on typical input 20 3 Module Buffer Extensible string buffers This module implements string buffers that automatically expand as necessary It provides accu mulative concatenation of strings in quasi linear time instead of quadratic time when strings are concatenated pairwise type t The abstract type of buffers val create int gt t create nreturns a fresh buffer initially empty The n parameter is the initial size of the internal string that holds the buffer contents That string is
424. nction over the set elements All operations over sets are purely applicative no side effects The implementation uses balanced binary trees and is therefore reasonably efficient insertion and membership take time logarithmic in the size of the set for instance module type OrderedType sig type t The type of the set elements val compare t gt t gt int A total ordering function over the set elements This is a two argument function f such that f e1 e2 is zero if the elements e1 and e2 are equal f e1 e2 is strictly negative if e1 is smaller than e2 and f e1 e2 is strictly positive if e1 is greater than e2 Example a suitable ordering function is the generic structural comparison function Pervasives compare end Input signature of the functor Set Make 20 28 module type S sig type elt The type of the set elements type t Chapter 20 The standard library 353 val val val val val val val val val val val val The type of sets empty t The empty set is_empty t gt bool Test whether a set is empty or not mem elt gt t gt bool mem x s tests whether x belongs to the set s add elt gt t gt t add x s returns a set containing all elements of s plus x If x was already in s s is returned unchanged singleton elt gt t singleton x returns the one element set containing only x remove elt gt t gt t remove x s returns a set
425. nd dst fill Ca b c t gt a gt unit Set all elements of a big array to a given value Genarray fill a v stores the value v in all elements of the big array a Setting only some elements of a to v can be achieved by applying Genarray fill to a sub array or a slice of a val map_file Unix file_descr gt a b Bigarray kind gt c Bigarray layout gt bool gt int array gt a b c t Memory mapping of a file as a big array Genarray map_file fd kind layout shared dims returns a big array of kind kind layout layout and dimensions as specified in dims The data contained in this big array are the contents of the file referred to by the file descriptor fd as opened previously with Unix openfile for example If shared is true all modifications performed on the array are reflected in the file This requires that fd be opened with write permissions If shared is false modifications performed on the array are done in memory only using copy on write of the modified pages the underlying file is not affected Genarray map_file is much more efficient than reading the whole file in a big array modifying that big array and writing it afterwards Chapter 29 The bigarray library 463 end To adjust automatically the dimensions of the big array to the actual size of the file the major dimension that is the first dimension for an array with C layout and the last dimension for an array with For
426. nd other resources such as file descriptors X Windows bitmaps etc For those blocks the in heap size of blocks is not a good measure of the quantity of resources allocated by the program The two arguments used and maz give the GC an idea of how much out of heap resources are consumed by the finalized block being allocated you give the amount of resources allocated to this object as parameter used and the maximum amount that you want to see in floating garbage as parameter max The units are arbitrary the GC cares only about the ratio used maz Chapter 18 Interfacing C with Objective Caml 257 For instance if you are allocating a finalized block holding an X Windows bitmap of w by h pixels and you d rather not have more than 1 mega pixels of unreclaimed bitmaps specify used w x h and max 1000000 Another way to describe the effect of the used and maz parameters is in terms of full GC cycles If you allocate many custom blocks with used mar 1 N the GC will then do one full cycle examining every object in the heap and calling finalization functions on those that are unreachable every N allocations For instance if used 1 and maz 1000 the GC will do one full cycle at least every 1000 allocations of custom blocks If your finalized blocks contain no pointers to out of heap resources or if the previous discussion made little sense to you just take used 0 and maz 1 But if you later find that the finalization functions are
427. ndard library to the search path inline n Set aggressiveness of inlining to n where n is a positive integer Specifying inline 0 prevents all functions from being inlined except those whose body is smaller than the call site Thus inlining causes no expansion in code size The default aggressiveness inline 1 allows slightly larger functions to be inlined resulting in a slight expansion in code size Higher values for the inline option cause larger and larger functions to become candidate for inlining but can result in a serious increase in code size linkall Forces all modules contained in libraries to be linked in If this flag is not given unreferenced modules are not linked in When building a library a flag setting the linkall flag forces all subsequent links of programs involving that library to link all the modules contained in the library noassert Turn assertion checking off assertions are not compiled This flag has no effect when linking already compiled files 170 noautolink When linking cmxa libraries ignore cclib and ccopt options potentially contained in the libraries if these options were given when building the libraries This can be useful if a library contains incorrect specifications of C libraries or C options in this case during linking set noautolink and pass the correct C libraries and options on the command line nolabels Ignore non optional labels in types Labels cannot be use
428. neral output functions type open_flag Open_rdonly open for reading Open_wronly open for writing Open_append open for appending always write at end of file Open_creat create the file if it does not exist Open_trunc empty the file if it already exists Open_excl fail if the file already exists Open_binary open in binary mode no conversion Open_text open in text mode may perform conversions Open_nonblock open in non blocking mode Opening modes for Pervasives open_out_gen 19 2 and Pervasives open_in_gen 19 2 Chapter 19 The core library 279 val val val val val val val val val val open_out string gt out_channel Open the named file for writing and return a new output channel on that file positionned at the beginning of the file The file is truncated to zero length if it already exists It is created if it does not already exists Raise Sys_error if the file could not be opened open_out_bin string gt out_channel Same as Pervasives open_out 19 2 but the file is opened in binary mode so that no translation takes place during writes On operating systems that do not distinguish between text mode and binary mode this function behaves like Pervasives open_out 19 2 open_out_gen open_flag list gt int gt string gt out_channel Open the named file for writing as above The extra argument mode specify the opening mode The extra argument perm speci
429. new_channel next nextkey 440 nice norm 296 norm2 not 269 Not_found npeek 361 nth 293 BD E57 nth_din Num 407 num 407 num_digits_big_int num_dims num_of_big_int num_of_int num_of_nat 410 num_of_ratio num_of_string 410 ocaml_version of _array of_channel 360 of_float of_int of _int32 of _list 360 of _nativeint 325 of_string 325 3 one 250 B20 B25 ES Oo open_box 300 open_connection open_flag 440 open_graph open_hbox 303 open_hovbox open_hvbox 303 open_in open_in_bin 281 open_in_gen 281 open_out open_out_bin 279 open_out_gen open_process open_process_ful1 386 open_process_in open_process_out open_tag open_tbox 303 BS O 860 INDEX TO THE LIBRARY open_temp_file 299 open_vbox 803 opendbm 440 opendir 385 openfile openTk option or OrderedType os_type 365 out_channel out _channel_length 280 282 out_channel_of_descr Out_of_memory output output_binary_int output _buffer output_byte output_char output_string output_value 280 over_max_boxes 302 pack 449 parent_dir_name 298 parse 288 parse_argv 289 Parse_error Parsing partition passwd_entry 392 pause 889 peek Pervasives 268 pipe pixels 449 place 450 plot 432 plots point_color polar poll Pop pos_in pos_out 483 position 327 pow
430. ng coercions would be unsafe and could only be combined with a type case possibly raising a runtime error However there is no such operation available in the language Be aware that subtyping and inheritance are not related Inheritance is a syntactic relation between classes while subtyping is a semantic relation between types For instance the class of colored points could have been defined directly without inheriting from the class of points the type of colored points would remain unchanged and thus still be a subtype of points The domain of a coercion can usually be omitted For instance one can define let to_point cp cp gt point val to_point point gt point lt fun gt In this case the function colored_point_to_point is an instance of the function to_point This is not always true however The fully explicit coercion is more precise and is sometimes unavoidable Consider for example the following class class c0 object method m lt gt method n O end class c0 object a method m a method n int end The object type c is an abbreviation for lt m a n int gt as a Consider now the type declaration class type c1 object method m c1 end class type c1 object method m c1 end Chapter 3 Objects in Caml 51 The object type c1 is an abbreviation for the type lt m a gt as a The coercion from an object of type cO to an object of type c1 is correct fu
431. ng to the given generic big array Raise Invalid_arg if the generic big array does not have exactly one dimension 470 val array2_of_genarray a b c Genarray t gt a b c Array2 t Return the two dimensional big array corresponding to the given generic big array Raise Invalid_arg if the generic big array does not have exactly two dimensions val array3_of_genarray a b c Genarray t gt a b c Array3 t Return the three dimensional big array corresponding to the given generic big array Raise Invalid_arg if the generic big array does not have exactly three dimensions Re shaping big arrays val reshape Ca b c Genarray t gt int array gt a b c Genarray t reshape b d1 dN converts the big array b to a N dimensional array of dimensions di dN The returned array and the original array b share their data and have the same layout For instance assuming that b is a one dimensional array of dimension 12 reshape b 13 4 returns a two dimensional array b of dimensions 3 and 4 If b has C layout the element x y of b corresponds to the element x 3 y of b If b has Fortran layout the element x y of b corresponds to the element x y 1 4 of b The returned big array must have exactly the same number of elements as the original big array b That is the product of the dimensions of b must be equal to i14 iN Otherwise Invalid_arg is raise
432. ning of each iteration of a loop while cond do bowtie body done for i a to b do bowtie body done Exceptions A function application followed by a function return is replaced by the compiler by a jump tail call optimization In this case no event is put after the function application 16 4 2 Starting the debugged program The debugger starts executing the debugged program only when needed This allows setting brea points or assigning debugger variables before execution starts There are several ways to start execution run Run the program until a breakpoint is hit or the program terminates step 0 Load the program and stop on the first event goto time Load the program and execute it until the given time Useful when you already know ap proximately at what time the problem appears Also useful to set breakpoints on function values that have not been computed at time 0 see section 16 5 The execution of a program is affected by certain information it receives when the debugger starts it such as the command line arguments to the program and its working directory The debugger provides commands to specify this information set arguments and cd These com mands must be used before program execution starts If you try to change the arguments or the working directory after starting your program the debugger will kill the program after asking for confirmation 16 4 3 Running the program The following commands execute the pro
433. not called often enough consider increasing the used maz ratio 18 9 3 Accessing custom blocks The data part of a custom block v can be accessed via the pointer Data_custom_val v This pointer has type void and should be cast to the actual type of the data stored in the custom block The contents of custom blocks are not scanned by the garbage collector and must therefore not contain any pointer inside the Caml heap In other terms never store a Caml value in a custom block and do not use Field Store_field nor modify to access the data part of a custom block Conversely any C data structure not containing heap pointers can be stored in a custom block 18 9 4 Writing custom serialization and deserialization functions The following functions defined in lt caml intext h gt are provided to write and read back the contents of custom blocks in a portable way Those functions handle endianness conversions when e g data is written on a little endian machine and read back on a big endian machine 258 Function Action serialize_int_1 Write a 1 byte integer serialize_int_2 Write a 2 byte integer serialize_int_4 Write a 4 byte integer serialize_int_8 Write a 8 byte integer serialize_float_4 Write a 4 byte float serialize_float_8 Write a 8 byte float serialize_block_1 Write an array of 1 byte quantities serialize_block_2 Write an array of 2 byte quantities serialize_block_4 Write an array of 4 byte quantities serialize_b
434. nstance points can be automatically adjusted to the nearest point on a grid as follows class adjusted_point x_init let origin x_init 10 10 in object val mutable x origin method get_x x method get_offset x origin method move d x lt x d end class adjusted_point int gt object val mutable x int method get_offset int method get_x int method move int gt unit end One could also raise an exception if the x_init coordinate is not on the grid In fact the same effect could here be obtained by calling the definition of class point with the value of the origin class adjusted_point x_init point x_init 10 10 class adjusted_point int gt point An alternative solution would have been to define the adjustment in a special allocation function let new_adjusted_point x_init new point x_init 10 10 val new_adjusted_point int gt point lt fun gt 36 However the former pattern is generally more appropriate since the code for adjustment is part of the definition of the class and will be inherited This ability provides class constructors as can be found in other languages Several constructors can be defined this way to build objects of the same class but with different initialization patterns an alternative is to use initializers as decribed below in section 3 4 3 2 Immediate objects There is another more direct way to create an ob
435. nt formatter gt int gt unit val pp_print_float formatter gt float gt unit val pp_print_char formatter gt char gt unit val pp_print_bool formatter gt bool gt unit val pp_print_break formatter gt int gt int gt unit val pp_print_cut formatter gt unit gt unit val pp_print_space formatter gt unit gt unit val pp_force_newline formatter gt unit gt unit val pp_print_flush formatter gt unit gt unit val pp_print_newline formatter gt unit gt unit val pp_print_if_newline formatter gt unit gt unit val pp_open_tbox formatter gt unit gt unit val pp_close_tbox formatter gt unit gt unit val pp_print_tbreak formatter gt int gt int gt unit val pp_set_tab formatter gt unit gt unit val pp_print_tab formatter gt unit gt unit val pp_set_tags formatter gt bool gt unit val pp_set_print_tags formatter gt bool gt unit val pp_set_mark_tags formatter gt bool gt unit val pp_get_print_tags formatter gt unit gt bool val pp_get_mark_tags formatter gt unit gt bool val pp_set_margin formatter gt int gt unit val pp_get_margin formatter gt unit gt int val pp_set_max_indent formatter gt int gt unit val pp_get_max_indent formatter gt unit gt int val pp_set_max_boxes formatter gt int gt unit Chapter 20 The standard library 309 val pp_get_max_boxes formatte
436. nt print_string repr method copy lt repr String copy repr gt method sub start len lt repr String sub s start len gt end class better_string string gt object a val repr string method copy a method get string gt int gt char method print unit method set string gt int gt char gt unit method sub int gt int gt a end As shown in the inferred type the methods copy and sub now return objects of the same type as the one of the class Chapter 5 Advanced examples with classes and modules 81 Another difficulty is the implementation of the method concat In order to concatenate a string with another string of the same class one must be able to access the instance variable externally Thus a method repr returning s must be defined Here is the correct definition of strings class ostring s object self mytype val repr s method repr repr method get n String get n method set n c String set nc method print print_string repr method copy lt repr String copy repr gt method sub start len lt repr String sub s start len gt method concat t mytype lt repr repr t repr gt end class ostring string gt object a val repr string method concat a gt a method copy a method get string gt int gt char method print unit method repr string method set string gt int g
437. nt it introduces a new identifier with a new scope However the standard library provides references which are mutable indirection cells or one element arrays with operators to fetch the current contents of the reference and to assign the contents Variables can then be emulated by let binding a reference For instance here is an in place insertion sort over arrays let insertion_sort a for i 1 to Array length a 1 do let val_i a i in let j ref i in while j gt O amp amp val_i lt a j 1 do Chapter 1 The core language 17 a j lt a C j 1 jee tj 1 done a j lt vali done val insertion_sort a array gt unit lt fun gt HH H H H References are also useful to write functions that maintain a current state between two calls to the function For instance the following pseudo random number generator keeps the last returned number in a reference let current_rand ref 0 val current_rand int ref contents 0 let random current_rand current_rand 25713 1345 current_rand val random unit gt int lt fun gt Again there is nothing magic with references they are implemented as a one field mutable record as follows type a ref mutable contents a type a ref mutable contents a let r r contents val a ref gt a lt fun gt let r newval r contents l
438. nt for method m method m string This method won t appear in the documentation method bar int end This value appears in the documentation since the Stop special comment in the class does not affect the parent module of the class val foo string The value bar does not appear in the documentation val bar string The type t does not appear either type t string The no stop option to ocamldoc causes the Stop special comments to be ignored 15 2 3 Syntax of documentation comments The inside of documentation comments consists of free form text with optional formatting annotations followed by optional tags giving more specific information about parameters version Chapter 15 The documentation generator ocamldoc 207 authors The tags are distinguished by a leading character Thus a documentation comment has the following shape The comment begins with a description which is text formatted according to the rules described in the next section The description continues until the first non escaped character author Mr Smith param x description for parameter x Some elements support only a subset of all Q tags Tags that are not relevant to the documented element are simply ignored For instance all tags are ignored when documenting type constructors record fields and class inheritance clauses Similarly a param tag on a class insta
439. nt l Long_val v returns the long int encoded in value v Val_int i returns the value encoding the int i Int_val v returns the int encoded in value v Val_bool xz returns the Caml boolean representing the truth value of the C integer z Bool_val v returns 0 if v is the Caml boolean false 1 if vis true Val_true Val_false represent the Caml booleans true and false 18 4 3 Accessing blocks Wosize_val v returns the size of the block v in words excluding the header Tag_val v returns the tag of the block v Field v n returns the value contained in the n field of the structured block v Fields are numbered from 0 to Wosize_val v 1 Store_field b n v stores the value v in the field number n of value b which must be a structured block Code_val v returns the code part of the closure v string_length v returns the length number of characters of the string v Byte v n returns the n character of the string v with type char Characters are num bered from 0 to string_length v 1 Byte_u v n returns the n character of the string v with type unsigned char Characters are numbered from 0 to string_length v 1 String_val v returns a pointer to the first byte of the string v with type char This pointer is a valid C string there is a null character after the last character in the string However Caml strings can contain embedded null characters that will confuse the usual C functions over
440. ntegers signed or unsigned Bigarray int8_signed_elt or Bigarray int8_unsigned_elt 29 1 e 16 bit integers signed or unsigned Bigarray int16_signed_el1t 29 1 or Bigarray int 16_unsigned_elt e Caml integers signed 31 bits on 32 bit architectures 63 bits on 64 bit architectures Bigarray int_elt 29 1 e 32 bit signed integer Bigarray int32_e1t 29 1 e 64 bit signed integers Bigarray int64_e1t 29 1 platform native signed integers 32 bits on 32 bit architectures 64 bits on 64 bit architectures Bigarray nativeint_elt 29 1 Each element kind is represented at the type level by one of the abstract types defined below type float32_elt type float64_elt type complex32_elt Chapter 29 The bigarray library 457 type type type type type type type type type type val val val val val val val val complex64_elt int8_signed_elt int8_unsigned_elt int16_signed_elt int16_unsigned_elt int_elt int32_elt int64_elt nativeint_elt Ca b kind To each element kind is associated a Caml type which is the type of Caml values that can be stored in the big array or read back from it This type is not necessarily the same as the type of the array elements proper for instance a big array whose elements are of kind float32_elt contains 32 bit single precision floats but reading or writing one of its elements from Caml uses the Caml type float which is 64 bit double precision floats Th
441. nter to a block allocated by malloc or to a C variable 18 2 1 Integer values Integer values encode 31 bit signed integers 63 bit on 64 bit architectures They are unboxed unallocated 238 18 2 2 Blocks Blocks in the heap are garbage collected and therefore have strict structure constraints Each block includes a header containing the size of the block in words and the tag of the block The tag governs how the contents of the blocks are structured A tag lower than No_scan_tag indicates a structured block containing well formed values which is recursively traversed by the garbage collector A tag greater than or equal to No_scan_tag indicates a raw block whose contents are not scanned by the garbage collector For the benefits of ad hoc polymorphic primitives such as equality and structured input output structured and raw blocks are further classified according to their tags as follows Tag Contents of the block 0 to No_scan_tag 1 A structured block an array of Caml objects Each field is a value Closure_tag A closure representing a functional value The first word is a pointer to a piece of code the remaining words are value containing the environment String_tag A character string Double_tag A double precision floating point number Double_array_tag An array or record of double precision floating point num bers Abstract_tag A block representing an abstract datatype Custom_tag A block representin
442. o and then ask users to provide the custom and cclib lmylib options themselves at link time ocamlc o myprog custom mylib cma cclib lmylib The former alternative is more convenient for the final users of the library however 18 1 4 Dynamically linking C code with Caml code Starting with OCaml 3 03 an alternative to static linking of C code using the custom code is provided In this mode the Caml linker generates a pure bytecode executable no embedded custom runtime system that simply records the names of dynamically loaded libraries containing the C code The standard Caml runtime system ocamlrun then loads dynamically these libraries and resolves references to the required primitives before executing the bytecode This facility is currently supported and known to work well under Linux and Windows the native Windows port It is supported but not fully tested yet under FreeBSD Tru64 Solaris and Trix It is not supported yet under other Unixes Cygwin for Windows and MacOS To dynamically link C code with Caml code the C code must first be compiled into a shared library under Unix or DLL under Windows This involves 1 compiling the C files with appro priate C compiler flags for producing position independent code and 2 building a shared library from the resulting object files The resulting shared library or DLL file must be installed in a place where ocamlrun can find it later at program start up time see section 1
443. o int gt int gt unit rmoveto dx dy translates the current point by the given vector current_x unit gt int Return the abscissa of the current point current_y unit gt int Return the ordinate of the current point current_point unit gt int int Return the position of the current point lineto int gt int gt unit Draw a line with endpoints the current point and the given point and move the current point to the given point rlineto int gt int gt unit Draw a line with endpoints the current point and the current point translated of the given vector and move the current point to this point curveto int int gt int int gt int int gt unit curveto b c d draws a cubic Bezier curve starting from the current point to point d with control points b and c and moves the current point to d draw_rect int gt int gt int gt int gt unit draw_rect x y w h draws the rectangle with lower left corner at x y width w and height h The current point is unchanged draw_poly_line int int array gt unit Chapter 25 The graphics library 433 draw_poly_line points draws the line that joins the points given by the array argument The array contains the coordinates of the vertices of the polygonal line which need not be closed The current point is unchanged val draw_poly int int array gt unit draw_poly polygon draws the given polygon The array contains the co
444. o aD Co M i 00 LN IN ON LN LON TN TN OTN gt Il Ae Kej a oa lt lt lt ni lt gt on ae a Cr T a os cP C c E abs 270 B21 B27 B38 abs_big_int abs_float abs_num 408 w 5 SSS oo vw x x a Ni SISS S iw fe S SI Sa S ZO N El 3 ONO N J N Ba E SHS Sy SISI L o0 NJL BE SIRS ie 475 accept access access_permission acos ada POG BTA STI B20 B2 B34 B33 EE 0 add_available_units 444 add_big_int add_buffer add_channel add_char 294 add_int_big_int add_interfaces 444 add_num add_string add_substitute add_substring 294 addr_info alarm align 289 allocated_bytes allow_only 444 allow_unsafe_modules 444 always anchor 449 anon_fun append appname_get 449 appname_set 449 approx_num_exp approx_num_fix Arg arg 296 argv Arith_status arith_status Array array Array1 arrayl_of_genarray Array2 64 array2_of_genarray 470 476 Array3 467 array3_of_genarray 470 asin 272 asr Assert_failure assoc assq at_exit atan atan2 auto_synchronize background Bad 289 basename 298 beginning _of_input 349 Big_int big_int 411 big_int_of_int big_int_of_num big_int_of_string Bigarray bind bind_class bind_tag 453
445. o and gee cmo is already loaded in memory just as if you had typed load foo cmo load bar cmo load gee cmo on entrance to the toplevel The modules Foo Bar and Gee are not opened though you still have to do open Foo yourself if this is what you wish Chapter 9 The toplevel system ocaml 159 9 6 Options The following command line options are recognized by ocamlmktop cclib libname Pass the Llibname option to the C linker when linking in custom runtime mode See the corresponding option for ocamlc in chapter 8 ccopt option Pass the given option to the C compiler and linker when linking in custom runtime mode See the corresponding option for ocamlc in chapter custom Link in custom runtime mode See the corresponding option for ocaml1c in chapter 8 I directory Add the given directory to the list of directories searched for compiled object code files cmo and cma o exec file Specify the name of the toplevel file produced by the linker The default is a out 160 Chapter 10 The runtime system ocamlrun The ocamlrun command executes bytecode files produced by the linking phase of the ocamlc command 10 1 Overview The ocamlrun command comprises three main parts the bytecode interpreter that actually ex ecutes bytecode files the memory allocator and garbage collector and a set of C functions that implement primitive operations such as input output Th
446. o four typical situations Abstract type no equation no representation When appearing in a module signature this definition specifies nothing on the type con structor besides its number of parameters its representation is hidden and it is assumed incompatible with any other type Type abbreviation an equation no representation This defines the type constructor as an abbreviation for the type expression on the right of the sign New variant type or record type no equation a representation This generates a new type constructor and defines associated constructors or fields through which values of that type can be directly built or inspected Re exported variant type or record type an equation a representation In this case the type constructor is defined as an abbreviation for the type expression given in the equation but in addition the constructors or fields given in the representation remain attached to the defined type constructor The type expression in the equation part must agree with the representation it must be of the same kind record or variant and have exactly the same constructors or fields in the same order with the same arguments The type variables appearing as type parameters can optionally be prefixed by or to indicate that the type constructor is covariant or contravariant with respect to this parameter This variance information is used to decide subtyping relations when checking the validity of gt
447. o ocamlc custom is to build separately a custom runtime system integrating the desired C libraries then generate pure bytecode executables not containing their own run time system that can run on this custom runtime This is achieved by the make_runtime and use_runtime flags to ocamlc For example to build a custom runtime system integrating the C parts of the Unix and Threads libraries do ocamlc make runtime o home me ocamlunixrun unix cma threads cma To generate a bytecode executable that runs on this runtime system do ocamlc use runtime home me ocamlunixrun o myprog unix cma threads cma your cmo and cma files The bytecode executable myprog can then be launched as usual myprog args or home me ocamlunixrun myprog args Notice that the bytecode libraries unix cma and threads cma must be given twice when building the runtime system so that ocamlc knows which C primitives are required and also when building the bytecode executable so that the bytecode from unix cma and threads cma is actually linked in 18 2 The value type All Caml objects are represented by the C type value defined in the include file cam1 mlvalues h along with macros to manipulate values of that type An object of type value is either e an unboxed integer e a pointer to a block inside the heap such as the blocks allocated through one of the alloc_ functions below e a pointer to an object outside the heap e g a poi
448. od it looks in the search path for a file named Mod cmi or mod cmi and loads the compiled interface contained in that file As a consequence renaming cmi files is not advised the name of a cmi file must always correspond to the name of the compilation unit it implements It is admissible to move them to another directory if their base name is preserved and the correct I options are given to the compiler The compiler will flag an error if it loads a cmi file that has been renamed Compiled bytecode files cmo files on the other hand can be freely renamed once created That s because the linker never attempts to find by itself the cmo file that implements a module with a given name it relies instead on the user providing the list of cmo files by hand 8 4 Common errors This section describes and explains the most frequently encountered error messages Cannot find file filename The named file could not be found in the current directory nor in the directories of the search path The filename is either a compiled interface file cmi file or a compiled bytecode file cmo file If filename has the format mod cmi this means you are trying to compile a file that references identifiers from module mod but you have not yet compiled an interface for module mod Fix compile mod mli or mod ml first to create the compiled interface mod cmi 150 If filename has the format mod cmo this means you are trying to link a bytecode object f
449. od length int method pop a method push a gt unit end 5 2 2 Hashtbl A simplified version of object oriented hash tables should have the following class type class type a b hash_table object method find a gt b method add a gt b gt unit end class type a b hash_table object method add a gt b gt unit method find a gt b end A simple implementation which is quite reasonable for small hastables is to use an association list class a b small_hashtbl a b hash_table object val mutable table method find key List assoc key table method add key valeur table lt key valeur table end class a b small_hashtbl a b hash_table HH H H A better implementation and one that scales up better is to use a true hash tables whose elements are small hash tables class a b hashtbl size a b hash_table object self val table Array init size fun i gt new small_hashtbl method private hash key Hashtbl hash key mod Array length table method find key table self hash key find key method add key table self hash key add key end class a b hashtbl int gt a b hash_table HHH HH H HH 84 5 2 3 Sets Implementing sets leads to another difficulty Indeed the method union needs to be able to access the internal
450. odule expr module expr module expr module expr module type definition let rec let binding and let binding external value name typexpr external declaration type definition exception definition class definition classtype definition module module name module name module type module type module expr module type modtype name module type open module path include module expr 6 11 1 Simple module expressions The expression module path evaluates to the module bound to the name module path The expression module expr evaluates to the same module as module expr The expression module expr module type checks that the type of module expr is a subtype of module type that is that all components specified in module type are implemented in module expr and their implementation meets the requirements given in module type In other terms it checks that the implementation module expr meets the type specification module type The whole expression evaluates to the same module as module expr except that all components not specified in module type are hidden and can no longer be accessed 6 11 2 Structures Structures struct end are collections of definitions for value names type names exceptions module names and module type names The definitions are evaluated in the order in which they appear in the structure The scope of the bindings performed by the definitions extend to the end of th
451. of the argument length of the longest sub list Iterators val iter a gt unit gt a list gt unit List iter f al an applies function f in turn to al an It is equivalent to begin f al f a2 f an end val map a gt b gt a list gt b list List map f a1 an applies function f to a1 an and builds the list f a1 f an with the results returned by f Not tail recursive val rev_map a gt b gt a list gt b list List rev_map f 1 gives the same result as List rev 20 17 List map 20 17 1 but is tail recursive and more efficient val fold_left Ca gt b gt a gt a gt b list gt a List fold_left f a b1 bn isf a b1 b2 bn val fold_right a gt b gt b gt a list gt b gt b List fold_right f a1 an bisf ai f a2 f an b Not tail recursive Iterators on two lists val iter2 a gt b gt unit gt a list gt b list gt unit List iter2 f a1 an b1 bn calls in turn f al b1 f an bn Raise Invalid_argument if the two lists have different lengths val map2 a gt b gt c gt a list gt b list gt c list List map2 f a1 an b1 bn is f a1 b1 f an bn Raise Invalid_argument if the two lists have different lengths Not tail recursive val rev_map2 a
452. of the first missing argument printing will then resume when the missing arguments are provided For example List iter printf x d y d_ 1 2 3 prints x 1 y 2 3 instead of the expected x 1 y 2 x 1 y 3 To get the expected behavior do List iter fun y gt printf x 4d y 4d 1 y 2 3 val printf a Pervasives out_channel unit Pervasives format gt a Same as Printf fprintf 20 24 but output on stdout val eprintf a Pervasives out_channel unit Pervasives format gt a Same as Printf fprintf 20 24 but output on stderr val sprintf a unit string Pervasives format gt a Same as Printf fprintf 20 24 but instead of printing on an output channel return a string containing the result of formatting the arguments val bprintf Buffer t gt a Buffer t unit Pervasives format gt a Same as Printf fprintf 20 24 but instead of printing on an output channel append the formatted arguments to the given extensible buffer see module Buffer val kprintf string gt a gt b unit string a format4 gt b kprintf k format arguments is the same as sprintf format arguments except that the resulting string is passed as argument to K the result of k is then returned as the result of kprintf 20 25 Module Queue First in first out queues This module implements queues FIFOs with in place modification type a t The type of queues containing elements of typ
453. on a non labeled argument appearing after this optional argument in the function type let test x 0 tly 0 O z 0 O x y 2045 val test x int gt y int gt unit gt z int gt unit gt int int int lt fun gt test Q z int gt unit gt int int int lt fun gt test x 2 72 3 Q int int int 2 0 3 Optional parameters may also commute with non optional or unlabelled ones as long as they are applied simultaneously By nature optional arguments do not commute with unlabeled arguments applied independently test y 2 728 O Oe int int int 3 2 0 test Q 7z 1 y 2 x 3 int int int 3 2 1 test O O 7z 1 This expression is not a function it cannot be applied 66 Here test is already 0 0 0 and cannot be further applied Optional arguments are actually implemented as option types If you do not give a default value you have access to their internal representation type a option None Some of a You can then provide different behaviors when an argument is present or not let bump step x match step with None gt x 2 Some y gt x y 35 val bump step int gt int gt int lt fun gt It may also be useful to relay an optional argument from a function call to another This can be done by prefixing the applied argument with This question mark disables the wrapping of optio
454. or and other parts of the run time system Without the rectypes option such ill founded recursive definitions are rejected by the type checker exception Undefined val force at gt a force x forces the suspension x and returns its result If x has already been forced Lazy force x returns the same value again without recomputing it If it raised an exception the same exception is raised again Raise Undefined if the forcing of x tries to force x itself recursively val force_val at gt a force_val x forces the suspension x and returns its result If x has already been forced force_val x returns the same value again without recomputing it Raise Undefined if the forcing of x tries to force x itself recursively If the computation of x raises an exception it is unspecified whether force_val x raises the same exception or Undefined val lazy_from_fun unit gt a gt at lazy_from_fun f is the same as lazy f but slightly more efficient val lazy_from_val a gt at lazy_from_val v returns an already forced suspension of v This is for special purposes only and should not be confused with lazy v val lazy_is_val a t gt bool lazy_is_val x returns true if x has already been forced and did not raise an exception Chapter 20 The standard library 327 20 16 Module Lexing The run time library for lexers generated by ocamllex Positions type position pos_fname string p
455. ordinates of the vertices of the polygon The current point is unchanged val draw_segments int int int int array gt unit draw_segments segments draws the segments given in the array argument Each segment is specified as a quadruple x0 yO x1 y1 where x0 yO and x1 y1 are the coordinates of the end points of the segment The current point is unchanged val draw_arc int gt int gt int gt int gt int gt int gt unit draw_arc x y rx ry al a2 draws an elliptical arc with center x y horizontal radius rx vertical radius ry from angle a1 to angle a2 in degrees The current point is unchanged val draw_ellipse int gt int gt int gt int gt unit draw_ellipse x y rx ry draws an ellipse with center x y horizontal radius rx and vertical radius ry The current point is unchanged val draw_circle int gt int gt int gt unit draw_circle x y r draws a circle with center x y and radius r The current point is unchanged val set_line_width int gt unit Set the width of points and lines drawn with the functions above Under X Windows set_line_width 0 selects a width of 1 pixel and a faster but less precise drawing algorithm than the one used when set_line_width 1 is specified Text drawing val draw_char char gt unit See Graphics draw_string val draw_string string gt unit Draw a character or a character string with lower left corner at current position After d
456. os_lnum int pos_bol int pos_cnum int A value of type position describes a point in a source file pos_fname is the file name pos_lnum is the line number pos_bol is the offset of the beginning of the line number of characters between the beginning of the file and the beginning of the line pos_cnum is the offset of the position number of characters between the beginning of the file and the position val dummy_pos position A value of type position guaranteed to be different from any valid position Lexer buffers type lexbuf refill_buff lexbuf gt unit mutable lex_buffer string mutable lex_buffer_len int mutable lex_abs_pos int mutable lex_start_pos int mutable lex_curr_pos int mutable lex_last_pos int mutable lex_last_action int mutable lex_eof_reached bool mutable lex_mem int array mutable lex_start_p position mutable lex_curr_p position The type of lexer buffers A lexer buffer is the argument passed to the scanning functions defined by the generated scanners The lexer buffer holds the current state of the scanner plus a function to refill the buffer from the input Note that the lexing engine will only manage the pos_cnum field of lex_curr_p by updating it with the number of characters read since the start of the lexbuf For the other fields to be accurate they must be initialised before the first use of the lexbuf and updated by the lexer actions
457. otice that the cons cells are small blocks and can be allocated with alloc_smal11 and filled by direct assignments on their fields value alloc_list_int int i1 int i2 Chapter 18 Interfacing C with Objective Caml 247 CAMLparamO CAMLlocal2 result r r alloc_small 2 0 Allocate a cons cell Field r 0 Val_int i2 car the integer i2 Field r 1 Val_int 0 cdr the empty list result alloc_small 2 0 Allocate the other cons cell Field result 0 Val_int ii car the integer il Field result 1 r cdr the first cons cell CAMLreturn result In the two examples above the list is built bottom up Here is an alternate way that proceeds top down It is less efficient but illustrates the use of modify value alloc_list_int int i1 int i2 CAMLparamO CAMLlocal2 tail r r alloc_small 2 0 Allocate a cons cell Field r 0 Val_int il car the integer i1 Field r 1 Val_int 0 A dummy value tail alloc_small 2 0 Allocate the other cons cell Field tail 0 Val_int i2 car the integer i2 Field tail 1 Val_int 0 cdr the empty list modify amp Field r 1 tail cdr of the result tail return rT It would be incorrect to perform Field r 1 tail directly because the allocation of tail has taken place since r was allocated tail is not registered as a root because there is no al
458. otify a gt event gt unit end Unsurprisingly the type of window is recursive let window new window_subject val window lt notify a gt event gt unit _ gt window_subject as a lt obj gt However the two classes of window_subject and window_observer are not mutually recursive let window_observer new window_observer val window_observer lt draw unit _ gt window_observer lt obj gt window add_observer window_observer unit window move 1 Position 1 unit Chapter 5 Advanced examples with classes and modules 87 Classes window_observer and window_subject can still be extended by inheritance For in stance one may enrich the subject with new behaviors and refined the behavior of the observer class observer richer_window_subject object self inherit observer window_subject val mutable size 1 method resize x size lt size x self notify_observers Resize val mutable top false method raise top lt true self notify_observers Raise method draw Printf printf Position d Size d n position size end class a richer_window_subject object b constraint a lt notify b gt event gt unit gt val mutable observers a list val mutable position int val mutable size int val mutable top bool method add_observer a gt unit method draw unit metho
459. ou can also use them in nested C blocks within the function Example value bar value vi value v2 value v3 CAMLparam3 v1 v2 v3 CAMLlocall result result alloc 3 0 CAMLreturn result Chapter 18 Interfacing C with Objective Caml 245 Rule 3 Assignments to the fields of structured blocks must be done with the Store_field macro for normal blocks or Store_double_field macro for arrays and records of floating point num bers Other assignments must not use Store_field nor Store_double_field Store_field b n v stores the value v in the field number n of value 6 which must be a block i e Is_block b must be true Example value bar value vi value v2 value v3 CAMLparam3 v1 v2 v3 CAMLlocali result result alloc 3 0 Store_field result 0 v1 Store_field result 1 v2 Store_field result 2 v3 CAMLreturn result Warning The first argument of Store_field and Store_double_field must be a variable declared by CAMLparam or a parameter declared by CAMLlocal to ensure that a garbage collection triggered by the evaluation of the other arguments will not invalidate the first argument after it is computed Rule 4 Global variables containing values must be registered with the garbage collector using the register_global_root function Registration of a global variable v is achieved by calling register_global_root amp v just before a valid value is stored in v for the first time
460. ove int mutable ev_ButtonNumber int mutable ev_Count int mutable ev_Detail string mutable ev_Focus bool mutable ev_Height int mutable ev_KeyCode int mutable ev_Mode string mutable ev_OverrideRedirect bool mutable ev_Place string mutable ev_State string mutable ev_Time int mutable ev_Width int mutable ev_MouseX int mutable ev_MouseY int mutable ev_Char string mutable ev_BorderWidth int mutable ev_SendEvent bool mutable ev_KeySymString string mutable ev_KeySymInt int mutable ev_RootWindow int mutable ev_SubWindow int mutable ev_Type int mutable ev_Widget Widget any Widget widget mutable ev_RootX int mutable ev_RootY int 451 452 Event related information accessible in callbacks type eventField Above BorderWidth ButtonNumber Char Count Detail Focus Height KeyCode KeySymInt KeySymString Mode MouseX MouseY OverrideRedirect Place RootWindow RootX RootY SendEvent State SubWindow Time Type Widget Width In order to access the above event information one has to pass a list of required event fields to the bind function val bind events event list gt extend bool gt breakable bool gt fields eventField list gt action eventInfo gt unit gt a Widget widget gt unit Bind a succession of events on a widg
461. p and next goto time Jump to the given time last count Go back to the latest time recorded in the execution history With an argument do it count times set history size Set the size of the execution history 16 4 5 Killing the program kill Kill the program being executed This command is mainly useful if you wish to recompile the program without leaving the debugger 16 5 Breakpoints A breakpoint causes the program to stop whenever a certain point in the program is reached It can be set in several ways using the break command Breakpoints are assigned numbers when set 220 for further reference The most comfortable way to set breakpoints is through the Emacs interface see section 16 10 break Set a breakpoint at the current position in the program execution The current position must be on an event i e neither at the beginning nor at the end of the program break function Set a breakpoint at the beginning of function This works only when the functional value of the identifier function has been computed and assigned to the identifier Hence this command cannot be used at the very beginning of the program execution when all identifiers are still undefined use goto time to advance execution until the functional value is available break module line Set a breakpoint in module module or in the current module if module is not given at the first event of line line break module line column Set a br
462. path fork unit gt int Fork a new process The returned integer is 0 for the child process the pid of the child process for the parent process wait unit gt int process_status Wait until one of the children processes die and return its pid and termination status waitpid wait_flag list gt int gt int process_status Same as Unix wait 21 but waits for the child process whose pid is given A pid of 1 means wait for any child A pid of 0 means wait for any child in the same process group as the current process Negative pid arguments represent process groups The list of options indicates whether waitpid should return immediately without waiting or also report stopped children system string gt process_status Execute the given command wait until it terminates and return its termination status The string is interpreted by the shell bin sh and therefore can contain redirections quotes variables etc The result WEXITED 127 indicates that the shell couldn t be executed getpid unit gt int Return the pid of the process getppid unit gt int Return the pid of the parent process nice int gt int Change the process priority The integer argument is added to the nice value Higher values of the nice value mean lower priorities Return the new nice value 378 Basic file input output type file_descr The abstract type of file descriptors val stdin file_descr
463. pe val Set_string of string Pervasives ref Set the reference to the string argument Int of int gt unit Call the function with an int argument Set_int of int Pervasives ref Set the reference to the int argument Float of float gt unit Call the function with a float argument Set_float of float Pervasives ref Set the reference to the float argument Tuple of spec list Take several arguments according to the spec list Symbol of string list string gt unit Take one of the symbols as argument and call the function with the symbol Rest of string gt unit Stop interpreting keywords and call the function with each remaining argument The concrete type describing the behavior associated with a keyword key string doc string usage_msg string anon_fun string gt unit parse key spec doc list gt anon_fun gt usage_msg gt unit Arg parse speclist anon_fun usage_msg parses the command line speclist is a list of triples key spec doc key is the option keyword it must start with a character spec gives the option type and the function to call when this option is found on the command line doc is a one line description of this option anon_fun is called on anonymous arguments The functions in spec and anon_fun are called in the same order as their arguments appear on the command line If an error occurs Arg parse exits the program after printing an error message as fol
464. pter 3 for more details and interface interface are their respective interfaces 134 Chapter 7 Language extensions This chapter describes language extensions and convenience features that are implemented in Ob jective Caml but not described in the Objective Caml reference manual 7 1 Integer literals for types int32 int64 and nativeint int32 literal integer literal 1 int64 literal integer literal L nativeint literal integer literal n An integer literal can be followed by one of the letters 1 L or n to indicate that this integer has type int32 int64 or nativeint respectively instead of the default type int for integer literals The library modules Int32 20 13 Int64 20 14 and Nativeint 20 20 provide operations on these integer types 7 2 Streams and stream parsers Streams and stream parsers are no longer part of the Objective Caml language but available through a Camlp4 syntax extension See the Camlp4 reference manual for more information Objec tive Caml programs that use streams and stream parsers can be compiled with the pp camlp4o op tion to ocamlc and ocamlopt For interactive use run ocaml and issue the load camlp4o cma command 7 3 Recursive definitions of values As mentioned in section 6 7 1 the letyrec binding construct in addition to the definition of recursive functions also supports a certain class of recursive definitions of non functional values such as let rec name
465. put c_igncr bool Ignore CR on input c_icrnl bool Map CR to NL on input c_ixon bool Recognize XON XOFF characters on input c_ixoff bool Emit XON XOFF chars to control input flow c_opost bool Enable output processing c_obaud int Output baud rate 0 means close connection c_ibaud int Input baud rate c_csize int Number of bits per character 5 8 c_cstopb int Number of stop bits 1 2 c_cread bool Reception is enabled c_parenb bool Enable parity generation and detection c_parodd bool Specify odd parity instead of even c_hupcl bool Hang up on last close c_clocal bool Ignore modem status lines c_isig bool Generate signal on INTR QUIT SUSP c_icanon bool Enable canonical processing line buffering and editing Chapter 21 mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable The unix library Unix system calls c_noflsh bool Disable flush after INTR QUIT SUSP c_echo bool Echo input characters c_echoe bool Echo ERASE to erase previous character c_echok bool Echo KILL to erase the current line c_echonl bool Echo NL even if c_echo is not set c_vintr char Interrupt character usually ctrl C c_vquit char Quit character usually ctrl c_verase char E
466. py a end class copy object self method copy Oo copy self end class copy object a method copy a end 56 Only the override can be used to actually override fields and only the 0o copy primitive can be used externally Cloning can also be used to provide facilities for saving and restoring the state of objects class backup object self mytype val mutable copy None method save copy lt Some lt copy None gt method restore match copy with Some x gt x None gt self end class backup object a val mutable copy a option method restore a method save unit end The above definition will only backup one level The backup facility can be added to any class using multiple inheritance class a backup_ref x object inherit a ref x inherit backup end class a backup_ref 2a gt object b val mutable copy b option val mutable x a method get a method restore b method save unit method set a gt unit end let rec get p n if n 0 then p get else get p restore n 1 val get lt get b restore a gt as a gt int gt b lt fun gt let p new backup_ref O in p save p set 1 p save p set 2 get p 0 get p 1 get p 2 get p 3 get p 4 int list 2 1 1 1 1 A variant of backup could retain all copies We then add a met
467. qual to this constant 104 Alias patterns The pattern pattern as value name matches the same values as pattern If the matching against pattern is successful the name name is bound to the matched value in addition to the bindings performed by the matching against pattern Parenthesized patterns The pattern pattern matches the same values as pattern A type constraint can appear in a parenthesized pattern as in pattern typexpr This constraint forces the type of pattern to be compatible with type Or patterns The pattern pattern pattern represents the logical or of the two patterns pattern and patterns A value matches pattern pattern either if it matches pattern or if it matches patterns The two sub patterns pattern and pattern must bind exactly the same identifiers to values having the same types Matching is performed from left to right More precisely in case some value v matches pattern pattern the bindings performed are those of pattern when v matches pattern Otherwise value v matches pattern whose bindings are performed Variant patterns The pattern constr pattern matches all variants whose constructor is equal to constr and whose argument matches pattern The pattern pattern pattern matches non empty lists whose heads match pattern and whose tails match patterns The pattern pattern pattern matches lists of length n whose elements match pattern
468. r Pervasives 19 2 rem int32 gt int32 gt int32 Integer remainder If y is not zero the result of Int32 rem x y satisfies the following properties Int32 zero lt Int32 rem x y lt Int32 abs y and x Int32 add Int32 mul Int32 div x y y Int32 rem x y Ify 0 Int32 rem x y raises Division_by_zero succ int32 gt int32 Successor Int32 succ x is Int32 add x Int32 one pred int32 gt int32 Predecessor Int32 pred x is Int32 sub x Int32 one abs int32 gt int32 Return the absolute value of its argument max_int int32 The greatest representable 32 bit integer 2 1 min_int int32 The smallest representable 32 bit integer 2 logand int32 gt int32 gt int32 Bitwise logical and logor int32 gt int32 gt int32 Bitwise logical or logxor int32 gt int32 gt int32 Bitwise logical exclusive or lognot int32 gt int32 Bitwise logical negation shift_left int32 gt int gt int32 Int32 shift_left x y shifts x to the left by y bits The result is unspecified if y lt O or y gt 32 shift_right int32 gt int gt int32 Int32 shift_right x y shifts x to the right by y bits This is an arithmetic shift the sign bit of x is replicated and inserted in the vacated bits The result is unspecified if y lt 0 or y gt 32 322 val val val val val val val val val shift_right_logical int32 gt int gt
469. r gt unit gt int val pp_over_max_boxes formatter gt unit gt bool val pp_set_ellipsis_text formatter gt string gt unit val pp_get_ellipsis_text formatter gt unit gt string val pp_set_formatter_out_channel formatter gt Pervasives out_channel gt unit val pp_set_formatter_output_functions formatter gt string gt int gt int gt unit gt unit gt unit gt unit val pp_get_formatter_output_functions formatter gt unit gt string gt int gt int gt unit unit gt unit val pp_set_all_formatter_output_functions formatter gt out string gt int gt int gt unit gt flush unit gt unit gt newline unit gt unit gt spaces int gt unit gt unit val pp_get_all_formatter_output_functions formatter gt unit gt string gt int gt int gt unit unit gt unit unit gt unit int gt unit val pp_set_formatter_tag_functions formatter gt formatter_tag_functions gt unit val pp_get_formatter_tag_functions formatter gt unit gt formatter_tag_functions These functions are the basic ones usual functions operating on the standard formatter are defined via partial evaluation of these primitives For instance print_string is equal to pp_print_string std_formatter printf like functions for pretty printing val fprintf formatter gt a formatter unit Pervasives format gt a fprintf ff format argi
470. r or 94 Prefix and infix symbols infix symbol prefix symbol operator char lt gt 7 1 amp 7 operator char operator char PS 41 s l2 14 21s lei ele Lhe Sequences of operator characters such as lt gt or are read as a single token from the infix symbol or prefix symbol class These symbols are parsed as prefix and infix operators inside expressions but otherwise behave much as identifiers Keywords The identifiers below are reserved as keywords and cannot be employed otherwise and as assert asr begin class constraint do done downto else end exception external false for fun function functor if in include inherit initializer land lazy let lor 1sl lsr lxor match method mod module mutable new object of open or private rec sig struct then to true try type val virtual when while with The following character sequences are also keywords l amp amp amp i C gt z Fa 2 gt os at gt AP lt lt gt gt gt lt gt I a lt I Note that the following identifiers are keywords of the Camlp4 extensions and should be avoided for compatibility reasons lt lt lt gt gt parser Ambiguities Lexical ambiguities are resolved according to the longest match rule when a character sequence can be decomposed into two tokens in several different ways the decomposition retained is the one with the
471. r evaluates to true The loop condition expr is evaluated and tested at the beginning of each iteration The whole while done expression evaluates to the unit value The expression for name expr to expr do expr done first evaluates the expressions expr and exprs the boundaries into integer values n and p Then the loop body expr is repeatedly evaluated in an environment where name is successively bound to the values n n 1 p 1 p The loop body is never evaluated if n gt p Chapter 6 The Objective Caml language 113 The expression for name expr downto expr do exprz done evaluates similarly except that name is successively bound to the values n n 1 p 1 p The loop body is never evaluated ifn lt p In both cases the whole for expression evaluates to the unit value Exception handling The expression try expr with pattern gt expr l pattern gt ezprn evaluates the expression expr and returns its value if the evaluation of expr does not raise any exception If the evaluation of expr raises an exception the exception value is matched against the patterns pattern to pattern If the matching against pattern succeeds the associated expression expr is evaluated and its value becomes the value of the whole try expression The evaluation of expr takes place in an environment enriched by the bindings performed during matching If several patterns match the value of expr the one that occurs
472. r method of the class Odoc_html1 info will look for the function associated to a custom tag and apply it to the text given to the tag If no function is associated to a custom tag then the method prints a warning message on stderr For other generators As for the HTML custom generator you can define a new ATEX resp man generator by inheriting from the class Odoc_latex latex resp Odoc_man man and adding your own tag handler to the field tag_functions 15 4 Adding command line options The command line analysis is performed after loading the module containing the documentation generator thus allowing command line options to be added to the list of existing ones Adding an option can be done with the function Odoc_args add_option string Arg spec string gt unit Note Existing command line options can be redefined using this function 15 4 1 Compilation and usage Defining a custom generator class in one file Let custom ml be the file defining a new generator class Compilation of custom ml can be per formed by the following command ocamlc I tocamldoc c custom ml The file custom cmo is created and can be used this way ocamldoc g custom cmo other options source files It is important not to give the html1 or any other option selecting a built in generator to ocamldoc which would result in using this generator instead of the one you just loaded Defining a custom generator class in several files It is possible to
473. r normally or because of an uncaught exception The functions are called in last in first out order the function most recently added with at_exit is called first Chapter 20 The standard library This chapter describes the functions provided by the Objective Caml standard library The modules from the standard library are automatically linked with the user s object code files by the ocamlc command Hence these modules can be used in standalone programs without having to add any cmo file on the command line for the linking phase Similarly in interactive use these globals can be used in toplevel phrases without having to load any cmo file in memory Unlike the Pervasive module from the core library the modules from the standard library are not automatically opened when a compilation starts or when the toplevel system is launched Hence it is necessary to use qualified identifiers to refer to the functions provided by these modules or to add open directives Conventions For easy reference the modules are listed below in alphabetical order of module names For each module the declarations from its signature are printed one by one in typewriter font followed by a short comment All modules and the identifiers they export are indexed at the end of this report Overview Here is a short listing by theme of the standard library modules 285 286 Data structures Char p character operations String p strin
474. r type weather type weather Rain of int The comment for constructor Rain Sun The comment for constructor Sun The comment for type my_record type my_record val foo int Comment for field foo val bar string Comment for field bar The comment for class my_class class my_class object A comment to describe inheritance from cl inherit cl The comment for the instance variable tutu val mutable tutu tutu The comment for toto val toto 1 val titi titi Comment for method toto method toto tutu I Comment for method m method m f float 1 end The comment for class type my_class_type class type my_class_type object The comment for the instance variable x val mutable x int The commend for method m method m int gt int end The comment for module Foo module Foo 206 struct The comment for x val x int A special comment in the class but not associated to any element end The comment for module type my_module_type module type my_module_type sig Comment for value x val x int end 15 2 2 The Stop special comment The special comment tells OCamldoc to discard elements placed after this comment up to the end of the current class class type module or module type For instance class type foo object comme
475. rameters typeconstr typexp adds the type equation typexp to the spec ification of the type component named typeconstr of the constrained signature The constraint module module path extended module path adds type equations to all type components of the sub structure denoted by module path making them equivalent to the corresponding type compo nents of the structure denoted by extended module path For instance if the module type name is bound to the signature sig type t module M sig type u end end then S with type t int denotes the signature sig type t int module M sig type u end end and S with module M N denotes the signature sig type t module M sig type u N u end end A functor taking two arguments of type S that share their t component is written functor A S B S with type t A t Constraints are added left to right After each constraint has been applied the resulting signa ture must be a subtype of the signature before the constraint was applied Thus the with operator can only add information on the type components of a signature but never remove information 130 6 11 Module expressions module implementations Module expressions are the module level equivalent of value expressions they evaluate to modules thus providing implementations for the specifications expressed in module types module expr module path struct definition end functor module name module type gt module expr m
476. rams object files and bytecode executable files are bigger and take longer to produce but the executable files run at exactly the same speed as if they had been compiled without g 16 2 Invocation 16 2 1 Starting the debugger The Objective Caml debugger is invoked by running the program ocamldebug with the name of the bytecode executable file as first argument ocamldebug options program arguments The arguments following program are optional and are passed as command line arguments to the program being debugged See also the set arguments command The following command line options are recognized I directory Add directory to the list of directories searched for source files and compiled files See also the directory command 215 216 s socket Use socket for communicating with the debugged program See the description of the com mand set socket section 16 8 6 for the format of socket c count Set the maximum number of simultaneously live checkpoints to count cd_ directory Run the debugger program from the working directory directory instead of the current di rectory See also the cd command emacs Tell the debugger it is executed under Emacs See section 16 10 for information on how to run the debugger under Emacs 16 2 2 Exiting the debugger The command quit exits the debugger You can also exit the debugger by typing an end of file character usually ctr1 D Typing an interrupt character
477. rary to signal cases where the library functions cannot complete normally For instance the List assoc function which returns the data associ ated with a given key in a list of key data pairs raises the predefined exception Not_found when the key does not appear in the list List assoc 1 0 zero 1 one string one List assoc 2 0 zero 1 one Exception Not_found Exceptions can be trapped with the try with construct let name_of_binary_digit digit try List assoc digit 0 zero 1 one with Not_found gt not a binary digit val name_of_binary_digit int gt string lt fun gt name_of_binary_digit 0 string zero name_of_binary_digit 1 string not a binary digit The with part is actually a regular pattern matching on the exception value Thus several exceptions can be caught by one try with construct Also finalization can be performed by trapping all exceptions performing the finalization then raising again the exception Chapter 1 The core language 19 let temporarily_set_reference ref newval funct let oldval ref in try ref newval let res funct in ref oldval res with x gt ref oldval raise x val temporarily_set_reference a ref gt a gt unit gt b gt b lt fun gt 1 7 Symbolic processing of expressions We finish this introduction wi
478. rase character usually DEL or ctrl H c_vkill char Kill line character usually ctrl U c_veof char End of file character usually ctrl D c_veol char Alternate end of line char usually none c_vmin int Minimum number of characters to read before the read request is satisfied c_vtime int Maximum read wait in 0 1s units c_vstart char Start character usually ctrl Q c_vstop char Stop character usually ctrl S val tcgetattr file_descr gt terminal_io Return the status of the terminal referred to by the given file descriptor 403 404 type setattr_when TCSANOW TCSADRAIN TCSAFLUSH val tcsetattr file_descr gt setattr_when gt terminal_io gt unit Set the status of the terminal referred to by the given file descriptor The second argument indicates when the status change takes place immediately TCSANOW when all pending output has been transmitted TCSADRAIN or after flushing all input that has been received but not read TCSAFLUSH TCSADRAIN is recommended when changing the output parameters TCSAFLUSH when changing the input parameters val tcsendbreak file_descr gt int gt unit Send a break condition on the given file descriptor The second argument is the duration of the break in 0 1s units 0 means standard duration 0 25s val tcdrain file_descr gt unit Waits until all output written on the given file descriptor has been trans
479. rawing the current position is set to the lower right corner of the text drawn val set_font string gt unit Set the font used for drawing text The interpretation of the arguments to set_font is implementation dependent val set_text_size int gt unit 434 Set the character size used for drawing text The interpretation of the arguments to set_text_size is implementation dependent val text_size string gt int int Return the dimensions of the given text if it were drawn with the current font and size Filling val fill_rect int gt int gt int gt int gt unit fill_rect x y w h fills the rectangle with lower left corner at x y width w and height h with the current color val fill_poly int int array gt unit Fill the given polygon with the current color The array contains the coordinates of the vertices of the polygon val fill_arc int gt int gt int gt int gt int gt int gt unit Fill an elliptical pie slice with the current color The parameters are the same as for Graphics draw_arc f val fill_ellipse int gt int gt int gt int gt unit Fill an ellipse with the current color The parameters are the same as for Graphics draw_ellipse l val fill_circle int gt int gt int gt unit Fill a circle with the current color The parameters are the same as for Graphics draw_circle Images type image The abstract type for images in internal repr
480. ray get Ca b c t gt int gt int gt a Array2 get a x y also written a x y returns the element of a at coordinates x y x and y must be within the bounds of a as described for Bigarray Genarray get 29 1 otherwise Invalid_arg is raised set Ca b c t gt int gt int gt a gt unit Array2 set a x y v or alternatively a x y lt v stores the value v at coordinates x y in a x and y must be within the bounds of a as described for Bigarray Genarray set 29 1 otherwise Invalid_arg is raised sub_left a b Bigarray c_layout t gt int gt int gt a b Bigarray c_layout t val 2 Extract a two dimensional sub array of the given two dimensional big array by restricting the first dimension See Bigarray Genarray sub_left for more details Array2 sub_left applies only to arrays with C layout sub_right a b Bigarray fortran_layout t gt int gt int gt a b Bigarray fortran_layout t 466 Extract a two dimensional sub array of the given two dimensional big array by restricting the second dimension See Bigarray Genarray sub_right for more details Array2 sub_right applies only to arrays with Fortran layout val slice_left Ca b Bigarray c_layout t gt int gt a b Bigarray c_layout Bigarray Array1 t Extract a row one dimensional slice of the given two dimensional big array The integer parameter is the index of the row
481. rays are as follows Big arrays are not limited in size unlike Caml arrays float array are limited to 2097151 elements on a 32 bit platform other array types to 4194303 elements Big arrays are multi dimensional Any number of dimensions between 1 and 16 is supported In contrast Caml arrays are mono dimensional and require encoding multi dimensional arrays as arrays of arrays Big arrays can only contain integers and floating point numbers while Caml arrays can contain arbitrary Caml data types However big arrays provide more space efficient storage of integer and floating point elements in particular because they support small types such as single precision floats and 8 and 16 bit integers in addition to the standard Caml types of double precision floats and 32 and 64 bit integers The memory layout of big arrays is entirely compatible with that of arrays in C and Fortran allowing large arrays to be passed back and forth between Caml code and C Fortran code with no data copying at all Big arrays support interesting high level operations that normal arrays do not provide effi ciently such as extracting sub arrays and slicing a multi dimensional array along certain dimensions all without any copying Programs that use the bigarray library must be linked as follows ocamlc other options bigarray cma other files ocamlopt other options bigarray cmxa other files For interactive use of the bigarray library do oc
482. re the same string and the source and destination chunks overlap Raise Invalid_argument if srcoff and len do not designate a valid substring of src or if dstoff and len do not designate a valid substring of dst concat string gt string list gt string String concat sep sl concatenates the list of strings s1 inserting the separator string sep between each iter char gt unit gt string gt unit String iter f s applies function f in turn to all the characters of s It is equivalent to f s 0 f s 1 f s String length s 1 O escaped string gt string Return a copy of the argument with special characters represented by escape sequences following the lexical conventions of Objective Caml If there is no special character in the argument return the original string itself not a copy index string gt char gt int String index s c returns the position of the leftmost occurrence of character c in string s Raise Not_found if c does not occur in s rindex string gt char gt int String rindex s c returns the position of the rightmost occurrence of character c in string s Raise Not_found if c does not occur in s index_from string gt int gt char gt int Same as String index 20 33 but start searching at the character position given as second argument String index s c is equivalent to String index_from s 0 c Chapter 20 The standard library 363 val rindex_from string
483. returns the number of bindings in tbl Multiple bindings are counted multiply so Hashtbl length gives the number of times Hashtbl iter calls it first argument Functorial interface module type HashedType sig type t The type of the hashtable keys val equal t gt t gt bool The equality predicate used to compare keys val hash t gt int A hashing function on keys It must be such that if two keys are equal according to equal then they have identical hash values as computed by hash Examples suitable equal hash pairs for arbitrary key types include Hashtb1 hash 20 12 for Chapter 20 The standard library end comparing objects by structure fun x y gt compare x y 0 Hashtbl hash 20 12 for comparing objects by structure and handling Pervasives nan 19 2 correctly and Hashtbl hash 20 12 for comparing objects by addresses e g for mutable or cyclic keys The input signature of the functor Hashtbl Make 20 12J module type S sig type key type at val create int gt at val clear a t gt unit val copy 2at gt at val add a t gt key gt a gt unit val remove a t gt key gt unit val find a t gt key gt a val find_all a t gt key gt a list val replace a t gt key gt a gt unit val mem a t gt key gt bool val iter key gt a gt unit gt a t gt unit val fold
484. ring v stringh string text _ text 15 2 5 Documentation tags tags Predefined tags The folowing table gives the list of predefined tags with their syntax and meaning 210 author string The author of the element One author by author tag There may be several author tags for the same element deprecated text The text should describe when the element was deprecated what to use as a replacement and possibly the reason for deprecation param id text Associate the given description text to the given parameter name id This tag is used for functions methods classes and functors raise Exc text Explain that the element may raise the exception Exc return tert Describe the return value and its possible values This tag is used for functions and methods see lt url gt text Add a reference to the URL between lt and gt with the given text as comment see filename test Add a reference to the given file name written between single quotes with the given text as comment see document name tert Add a reference to the given document name written be tween double quotes with the given text as comment since string Indicates when the element was introduced version string The version number for the element Custom tags You can use custom tags in the documentation comments but they will have no effect if the generator used does not h
485. rmatter_output_functions unit gt string gt int gt int gt unit unit gt unit Return the current output functions of the pretty printer Changing the meaning of printing tags type formatter_tag_functions mark_open_tag tag gt string mark_close_tag tag gt string print_open_tag tag gt unit print_close_tag tag gt unit 306 The tag handling functions specific to a formatter mark versions are the tag marking functions that associate a string marker to a tag in order for the pretty printing engine to flush those markers as 0 length tokens in the output device of the formatter print versions are the tag printing functions that can perform regular printing when a tag is closed or opened val set_formatter_tag_functions formatter_tag_functions gt unit set_formatter_tag_functions tag_funs changes the meaning of opening and closing tags to use the functions in tag_funs When opening a tag name t the string t is passed to the opening tag marking function the mark_open_tag field of the record tag_funs that must return the opening tag marker for that name When the next call to close_tag happens the tag name t is sent back to the closing tag marking function the mark_close_tag field of record tag_funs that must return a closing tag marker for that name The print_ field of the record contains the functions that are called at tag opening and tag closing time to output regular
486. rn gt expr matches the value of expr against the patterns pattern to pattern If the matching against pattern succeeds the associated expression expr is evaluated and its value becomes the value of the whole match expression The evaluation of expr takes place in an environment enriched by the bindings performed during matching If several patterns match the value of expr the one that occurs first in the match expression is selected If none of the patterns match the value of expr the exception Match_failure is raised Boolean operators The expression expr amp amp expr evaluates to true if both expr and expr evaluate to true oth erwise it evaluates to false The first component expr is evaluated first The second com ponent expr is not evaluated if the first component evaluates to false Hence the expression expr amp amp expr behaves exactly as if expr then expr else false The expression expr expr evaluates to true if one of expr and expr evaluates to true otherwise it evaluates to false The first component expr is evaluated first The second component exprs is not evaluated if the first component evaluates to true Hence the expression expr expr behaves exactly as if expr then true else exprs The boolean operator amp is synonymous for amp amp The boolean operator or is synonymous for Loops The expression while expr do expr done repeatedly evaluates expry while exp
487. rn the size number of characters of the regular file on which the given channel is opened If the channel is opened on a file that is not a regular file the result is meaningless The returned size does not take into account the end of line translations that can be performed when reading from a channel opened in text mode close_in in_channel gt unit Close the given channel Input functions raise a Sys_error exception when they are applied to a closed input channel except close_in which does nothing when applied to an already closed channel Note that close_in may raise Sys_error if the operating system signals an error close_in_noerr in_channel gt unit Same as close_in but ignore all errors set_binary_mode_in in_channel gt bool gt unit set_binary_mode_in ic true sets the channel ic to binary mode no translations take place during input set_binary_mode_out ic false sets the channel ic to text mode depending on the operating system some translations may take place during input For instance under Windows end of lines will be translated from r n to n This function has no effect under operating systems that do not distinguish between text mode and binary mode Operations on large files module LargeFile sig val seek_out Pervasives out_channel gt int64 gt unit val pos_out Pervasives out_channel gt int64 val out_channel_length Pervasives out_channel gt int64 Chapter 19 The core librar
488. rns a pair of sets s1 s2 where s1 is the set of all the elements of s that satisfy the predicate p and s2 is the set of all the elements of s that do not satisfy p cardinal t gt int Return the number of elements of a set elements t gt elt list Return the list of all elements of the given set The returned list is sorted in increasing order with respect to the ordering Ord compare where Ord is the argument given to Set Make 20 28 min_elt t gt elt Return the smallest element of the given set with respect to the Ord compare ordering or raise Not_found if the set is empty max_elt t gt elt Same as Set S min_elt 20 28 but returns the largest element of the given set choose t gt elt Return one element of the given set or raise Not_found if the set is empty Which element is chosen is unspecified but equal elements will be chosen for equal sets Chapter 20 The standard library 355 val split elt gt t gt t bool t split x s returns a triple 1 present r where 1 is the set of elements of s that are strictly less than x r is the set of elements of s that are strictly greater than x present is false if s contains no element equal to x or true if s contains an element equal to x end Output signature of the functor Set Make 20 28 module Make functor Ord OrderedType gt S with type elt Ord t Functor building an implementation of the set structure given a
489. rns an object of the same type The type of Oo copy is different from type lt gt gt lt gt as each ellipsis represents a different set of methods Ellipsis actually behaves as a type variable let p new point 5 val p point lt obj gt let q Oo copy p val q lt get_offset int get_x int move int gt unit gt lt obj gt q move 7 p get_x q get_x int int 5 12 In fact 0o copy p will behave as p copy assuming that a public method copy with body lt gt has been defined in the class of p Objects can be compared using the generic comparison functions and lt gt Two objects are equal if and only if they are physically equal In particular an object and its copy are not equal let q Oo copy p val q lt get_offset int get_x int move int gt unit gt lt obj gt p q P P35 bool bool false true Other generic comparissons such as lt lt can also be used on objects The relation lt defines an unspecified but strict ordering on objets The ordering relationship between two objects is fixed once for all after the two objects have been created and it is not affected by mutation of fields Cloning and override have a non empty intersection They are interchangeable when used within an object and without overriding any field class copy object method copy lt gt end class copy object a method co
490. rue Two type constructors can have the same name but actually represent different types This can happen if a type constructor is redefined Example type foo A B let f function A gt 0O B gt 1 type foo C D f C This result in the error message expression C of type foo cannot be used with type foo The type of this expression t contains type variables that cannot be generalized Type variables a b in a type t can be in either of two states generalized which means that the type tis valid for all possible instantiations of the variables and not gener alized which means that the type tis valid only for one instantiation of the variables In a let binding let name expr the type checker normally generalizes as many type variables as possible in the type of expr However this leads to unsoundness a well typed program can crash in conjunction with polymorphic mutable data structures To avoid this general ization is performed at let bindings only if the bound expression expr belongs to the class of syntactic values which includes constants identifiers functions tuples of syntactic values etc In all other cases for instance expr is a function application a polymorphic mutable could have been created and generalization is therefore turned off for all variables occuring in contravariant or non variant branches of the type For instance if the type of a non value is a list the variable is gener
491. s e the names of the C object files and libraries o and a files that implement the required primitives Under Unix and Windows a library named libname a residing in one of the standard library directories can also be specified as cclib lname If you are using the native code compiler ocamlopt the custom flag is not needed as the final linking phase of ocamlopt always builds a standalone executable To build a mixed Caml C executable execute the ocamlopt command with e the names of the desired Caml native object files cmx and cmxa files e the names of the C object files and libraries 0 a so or d11 files that implement the required primitives Starting with OCaml 3 00 it is possible to record the custom option as well as the names of C libraries in a Caml library file cma or cmxa For instance consider a Caml library mylib cma built from the Caml object files a cmo and b cmo which reference C code in libmylib a If the library is built as follows Chapter 18 Interfacing C with Objective Caml 235 ocamlc a o mylib cma custom a cmo b cmo cclib lmylib users of the library can simply link with mylib cma ocamlc o myprog mylib cma and the system will automatically add the custom and cclib lmylib options achieving the same effect as ocamlc o myprog custom a cmo b cmo cclib lmylib The alternative of course is to build the library without extra options ocamlc a o mylib cma a cmo b cm
492. s with size greater than Max_young_wosize The constant Max_young_wosize is declared in the Chapter 18 Interfacing C with Objective Caml 243 include file mlvalues h It is guaranteed to be at least 64 words so that any block with constant size less than or equal to 64 can be assumed to be small For blocks whose size is computed at run time the size must be compared against Max_young_wosize to determine the correct allocation procedure alloc_small n t returns a fresh small block of size n lt Max_young_wosize words with tag t If this block is a structured block i e if t lt No_scan_tag then the fields of the block initially containing garbage must be initialized with legal values using direct assignment to the fields of the block before the next allocation alloc_shr n t returns a fresh block of size n with tag t The size of the block can be greater than Max_young_wosize It can also be smaller but in this case it is more efficient to call alloc_small instead of alloc_shr If this block is a structured block i e if t lt No_scan_tag then the fields of the block initially containing garbage must be initialized with legal values using the initialize function described below before the next allocation 18 4 5 Raising exceptions Two functions are provided to raise two standard exceptions failwith s where s is a null terminated C string with type char raises exception Failure with argument s inva
493. s the two compilers should generate code that behave identically e The following operations abort the program via an hardware trap or fatal Unix signal instead of raising an exception stack overflow except on IA32 Linux on the Alpha processor only floating point operations involving infinite or denormalized numbers all other processors supported by ocamlopt treat these numbers correctly as per the IEEE 754 standard In particular notice that stack overflow caused by excessively deep recursion is reported by most Unix kernels as a segmentation violation signal 174 e Signals are detected only when the program performs an allocation in the heap That is if a signal is delivered while in a piece of code that does not allocate its handler will not be called until the next heap allocation The best way to avoid running into those incompatibilities is to never trap the Stack_overflow exception thus treating it as a fatal error both with the bytecode compiler and with the native code compiler Chapter 12 Lexer and parser generators ocamllex ocamlyacc This chapter describes two program generators ocamllex that produces a lexical analyzer from a set of regular expressions with associated semantic actions and ocamlyacc that produces a parser from a grammar with associated semantic actions These program generators are very close to the well known lex and yacc commands that can be found in most C progra
494. s aux cmi ocamlc c Aux ml produces aux cmo ocamlc c Main mli produces main cmi ocamlc c Main ml produces main cmo ocamlc o theprogram Aux cmo Main cmo The program behaves exactly as if the following phrases were entered at top level module Aux sig contents of Aux mli end struct contents of Aux ml end module Main sig contents of Main mli end struct contents of Main ml end In particular Main can refer to Aux the definitions and declarations contained in Main ml and Main mli can refer to definition in Aux m1 using the Aux ident notation provided these definitions are exported in Aux mli The order in which the cmo files are given to ocaml during the linking phase determines the order in which the module definitions occur Hence in the example above Aux appears first and Main can refer to it but Aux cannot refer to Main Notice that only top level structures can be mapped to separately compiled files but not func tors nor module types However all module class objects can appear as components of a structure so the solution is to put the functor or module type inside a structure which can then be mapped to a file Chapter 3 Objects in Caml Chapter written by J r me Vouillon Didier R my and Jacques Garrigue This chapter gives an overview of the object oriented features of Objective Caml 3 1 Classes and objects The class point below defines one instance variable x
495. s interface in file grammar mli The generated module defines one parsing function per entry point in the grammar These functions have the same names as the entry points Parsing functions take as arguments a lexical 180 analyzer a function from lexer buffers to tokens and a lexer buffer and return the semantic attribute of the corresponding entry point Lexical analyzer functions are usually generated from a lexer specification by the ocamllex program Lexer buffers are an abstract data type implemented in the standard library module Lexing Tokens are values from the concrete type token defined in the interface file grammar mli produced by ocamlyacc 12 4 Syntax of grammar definitions Grammar definitions have the following format header declarations Ah rules Ah trailer Comments are enclosed between and as in C in the declarations and rules sections and between and as in Caml in the header and trailer sections 12 4 1 Header and trailer The header and the trailer sections are Caml code that is copied as is into file grammar ml Both sections are optional The header goes at the beginning of the output file it usually contains open directives and auxiliary functions required by the semantic actions of the rules The trailer goes at the end of the output file 12 4 2 Declarations Declarations are given one per line They all start with a sign token symbol symbol Dec
496. s than any other float value This treatment of nan ensures that compare defines a total ordering relation compare applied to functional values may raise Invalid_argument compare applied to cyclic structures may not terminate The compare function can be used as the comparison function required by the Set Make 20 28 and Map Make 20 18 functors as well as the List sort 20 17 and Array sort 20 2 functions min a gt a gt a Return the smaller of the two arguments max a gt a gt a Return the greater of the two arguments a gt a gt bool e1 e2 tests for physical equality of e1 and e2 On integers and characters physical equality is identical to structural equality On mutable structures e1 e2 is true if and only if physical modification of e1 also affects e2 On non mutable structures the behavior of is implementation dependent however it is guaranteed that e1 e2 implies compare e1 e2 0 a gt a gt bool Negation of Pervasives 19 2 Boolean operations val val not bool gt bool The boolean negation amp amp bool gt bool gt bool The boolean and Evaluation is sequential left to right in e1 amp amp e2 e1 is evaluated first and if it returns false e2 is not evaluated at all 270 val amp bool gt bool gt bool Deprecated Pervasives amp amp should be used instead val
497. scription of custom below e Arguments ending in so d11 under Windows are assumed to be C shared libraries DLLs During linking they are searched for external C functions referenced from the Caml code and their names are written in the generated bytecode executable The run time system ocamlrun then loads them dynamically at program start up time The output of the linking phase is a file containing compiled bytecode that can be executed by the Objective Caml bytecode interpreter the command named ocamlrun If caml out is the name of the file produced by the linking phase the command ocamlrun caml out arg argg TOn executes the compiled code contained in caml out passing it as arguments the character strings arg to arg See chapter 10 for more details On most systems the file produced by the linking phase can be run directly as in caml out arg argg aTGn The produced file has the executable bit set and it manages to launch the bytecode interpreter by itself 8 2 Options The following command line options are recognized by ocamlc a Build a library cma file with the object files cmo files given on the command line instead of linking them into an executable file The name of the library must be set with the o option If custom cclib or ccopt options are passed on the command line these options are stored in the resulting cma library Then linking with this library automatically adds back t
498. se two types being Chapter 4 Labels and variants 67 incompatible internally normal and optional arguments are different a type error occurs when applying bump_it to the real bump We will not try here to explain in detail how type inference works One must just understand that there is not enough information in the above program to deduce the correct type of g or bump That is there is no way to know whether an argument is optional or not or which is the correct order by looking only at how a function is applied The strategy used by the compiler is to assume that there are no optional arguments and that applications are done in the right order The right way to solve this problem for optional parameters is to add a type annotation to the argument bump let bump_it bump step int gt int gt int x bump step 2 x val bump_it step int gt int gt int gt int gt int lt fun gt bump_it bump 1 jint 3 In practive such problems appear mostly when using objects whose methods have optional argu ments so that writing the type of object arguments is often a good idea Normally the compiler generates a type error if you attempt to pass to a function a parameter whose type is different from the expected one However in the specific case where the expected type is a non labeled function type and the argument is a function expecting optional parameters the compiler will attempt to transform the argu
499. sed only to initialize Sys argv but not for finding the name of the executable file The native code compiler ocamlopt also supports the output obj option causing it to output a C object file containing the native code for all Caml modules on the command line as well as the Caml startup code Initialization is performed by calling caml_startup as in the case of the bytecode compiler For the final linking phase in addition to the object file produced by output obj you will have to provide the Objective Caml runtime library libcamlrun a for bytecode libasmrun a for native code as well as all C libraries that are required by the Caml libraries used For instance assume the Caml part of your program uses the Unix library With ocamlc you should do ocamlc output obj o camlcode o unix cma other cmo and cma files cc o myprog C objects and libraries camlcode o L usr local lib ocaml lunix lcamlrun With ocamlopt you should do ocamlopt output obj o camlcode o unix cmxa other cmx and cmxa files cc o myprog C objects and libraries camlcode o L usr local lib ocaml lunix lasmrun Chapter 18 Interfacing C with Objective Caml 253 Warning On some ports special options are required on the final linking phase that links to gether the object file produced by the output obj option and the remainder of the program Those options are shown in the configuration file config Makefile generated during compilation of Ob jective Cam
500. sentable integers infinity float Positive infinity neg_infinity float Negative infinity nan float A special floating point value denoting the result of an undefined operation such as 0 0 0 0 Stands for not a number Any floating point operation with nan as argument returns nan as result As for floating point comparisons lt lt gt and gt return false and lt gt returns true if one or both of their arguments is nan max_float float The largest positive finite value of type float min_float float The smallest positive non zero non denormalized value of type float epsilon_float float The smallest positive float x such that 1 0 x lt gt 1 0 type fpclass FP_normal Normal number none of the below FP_subnormal Number very close to 0 0 has reduced precision FP_zero Number is 0 0 or 0 0 FP_infinite Number is positive or negative infinity FP_nan Not a number result of an undefined operation Chapter 19 The core library 275 The five classes of floating point numbers as determined by the Pervasives classify_float function val classify_float float gt fpclass Return the class of the given floating point number normal subnormal zero infinite or not a number String operations More string operations are provided in module String 20 33 val string gt string gt string String concatenation Character operations More
501. ser I directory Add the given directory to the list of directories searched for source and compiled files By default only the standard library directory is searched The standard library can also be changed by setting the OCAMLLIB environment variable nolabels Ignore non optional labels in types Labels cannot be used in applications and parameter order becomes strict oldui Old multi window interface The default is now more like Smalltalk s class browser rectypes Allow arbitrary recursive types during type checking By default only recursive types where the recursion goes through an object type are supported w warning list Enable or disable warnings according to the argument warning list 191 192 Most options can also be modified inside the application by the Modules Path editor and Compiler Preferences commands They are inherited when you start a toplevel shell 14 2 Viewer This is the first window you get when you start OCam Browser It displays a search window and the list of modules in the load path At the top a row of menus e File Open and File Editor give access to the editor e File Shell creates an Objective Caml subprocess in a shell e View Show all defs displays the signature of the currently selected module e View Search entry shows hides the search entry just below the menu bar e Modules Path editor changes the load path Modules Reset cache rescans the load path and res
502. ses cclib ltermcap instead of cclib lcurses 18 7 Advanced topic callbacks from C to Caml So far we have described how to call C functions from Caml In this section we show how C functions can call Caml functions either as callbacks Caml calls C which calls Caml or because the main program is written in C 250 18 7 1 Applying Caml closures from C C functions can apply Caml functional values closures to Caml values The following functions are provided to perform the applications e callback f a applies the functional value f to the value a and return the value returned by f e callback2 f a b applies the functional value f which is assumed to be a curried Caml function with two arguments to a and b e callback3 f a b c applies the functional value f a curried Caml function with three arguments to a b and c e callbackN f n args applies the functional value fto the n arguments contained in the array of values args If the function f does not return but raises an exception that escapes the scope of the application then this exception is propagated to the next enclosing Caml code skipping over the C code That is if a Caml function f calls a C function g that calls back a Caml function h that raises a stray exception then the execution of g is interrupted and the exception is propagated back into f If the C code wishes to catch exceptions escaping the Caml function it can use the func tions cal
503. set_max_indent d sets the value of the maximum indentation limit to d in characters once this limit is reached boxes are rejected to the left if they do not fit on the current line Nothing happens if d is smaller than 2 If d is too large the limit is set to the maximum admissible value which is greater than 10710 val get_max_indent unit gt int Return the value of the maximum indentation limit in characters Formatting depth maximum number of boxes allowed before ellipsis val set_max_boxes int gt unit set_max_boxes max sets the maximum number of boxes simultaneously opened Material inside boxes nested deeper is printed as an ellipsis more precisely as the text returned by get_ellipsis_text Nothing happens if max is smaller than 2 val get_max_boxes unit gt int Returns the maximum number of boxes allowed before ellipsis val over_max_boxes unit gt bool Tests if the maximum number of boxes allowed have already been opened Chapter 20 The standard library 303 Advanced formatting val open_hbox unit gt unit open_hbox opens a new pretty printing box This box is horizontal the line is not split in this box new lines may still occur inside boxes nested deeper val open_vbox int gt unit open_vbox d opens a new pretty printing box with offset d This box is vertical every break hint inside this box leads to a new line When a new line is printed in the box d is a
504. sign of the float bits 62 to 52 represent the biased exponent bits 51 to 0 represent the mantissa val float_of_bits int64 gt float Return the floating point number whose internal representation according to the IEEE 754 floating point double format bit layout is the given int64 type t int64 An alias for the type of 64 bit integers val compare t gt t gt int The comparison function for 64 bit integers with the same specification as Pervasives compare 19 2 Along with the type t this function compare allows the module Int64 to be passed as argument to the functors Set Make 20 28 and Map Make 20 18 326 20 15 Module Lazy Deferred computations type a t a lazy_t A value of type a Lazy t is a deferred computation called a suspension that has a result of type a The special expression syntax lazy expr makes a suspension of the computation of expr without computing expr itself yet Forcing the suspension will then compute expr and return its result Note lazy_t is the built in type constructor used by the compiler for the lazy keyword You should not use it directly Always use Lazy t instead Note if the program is compiled with the rectypes option ill founded recursive definitions of the form let rec x lazy x or let rec x lazy lazy lazy x are accepted by the type checker and lead when forced to ill formed values that trigger infinite loops in the garbage collect
505. sses type inet_addr The abstract type of Internet addresses val inet_addr_of_string string gt inet_addr Conversion from the printable representation of an Internet address to its internal representation The argument string consists of 4 numbers separated by periods XXX YYY ZZZ TTT for Pv4 addresses and up to 8 numbers separated by colons for IPv6 addresses Raise Failure when given a string that does not match these formats val string_of_inet_addr inet_addr gt string Return the printable representation of the given Internet address See Unix inet_addr_of_string for a description of the printable representation val inet_addr_any inet_addr A special IPv4 address for use only with bind representing all the Internet addresses that the host machine possesses val inet_addr_loopback inet_addr A special IPv4 address representing the host machine 127 0 0 1 val inet6_addr_any inet_addr A special IPv6 address for use only with bind representing all the Internet addresses that the host machine possesses val inet6_addr_loopback inet_addr A special IPv6 address representing the host machine 1 394 Sockets type socket_domain PF_UNIX Unix domain PF_INET Internet domain IPv4 PF_INET6 Internet domain IPv6 The type of socket domains type socket_type SOCK_STREAM Stream socket SOCK_DGRAM Datagram socket SOCK_RAW Raw socket SOCK_SEQPACKET Sequenc
506. stallation in a directory included in you path No toplevel is available but you can load the library from the standard toplevel with the following commands 447 448 directory labltk load labltk cma You can also load it directly from the command line C ocaml bin gt ocaml I labltk labltk cma The lab1tk library is composed of a large number of modules Bell Imagebitmap Button Imagephoto Canvas Label Checkbutton Listbox Clipboard Menu Dialog Menubutton Entry Message Focus Option Frame Optionmenu Grab Pack Grid Palette Place Radiobutton Scale Scrollbar Selection Text Tk Tkwait Toplevel Winfo Wm Giving a detailed account of each of these module would be impractical here We will just present some of the basic functions in the module Tk Note that for most other modules information can be found in the Tcl man page of their name 28 1 Module Tk Basic functions and types for LablTk Initialization and termination val openTk display string gt clas string gt unit gt Widget toplevel Widget widget Initialize LablTk and open a toplevel window display is described according to the X11 conventions clas is used for the X11 resource mechanism val mainLoop unit gt unit Start the main event loop val closeTk unit gt unit Quit the main loop and close all open windows val destroy a Widget widget gt unit Destroy an individual widget Chapter 28
507. sts The integer argument is the maximal number of pending requests type shutdown_command SHUTDOWN_RECEIVE Close for receiving SHUTDOWN_SEND Close for sending SHUTDOWN_ALL Close both The type of commands for shutdown val shutdown file_descr gt shutdown_command gt unit Shutdown a socket connection SHUTDOWN_SEND as second argument causes reads on the other end of the connection to return an end of file condition SHUTDOWN_RECEIVE causes writes on the other end of the connection to return a closed pipe condition SIGPIPE signal val getsockname file_descr gt sockaddr Return the address of the given socket val getpeername file_descr gt sockaddr Return the address of the host connected to the given socket type msg_flag MSG_OOB MSG_DONTROUTE MSG_PEEK The flags for Unix recv Unix recvfrom 21 1 Unix send 21 1 and Unix sendto val recv file_descr gt string gt int gt int gt msg_flag list gt int Receive data from a connected socket 396 val recvfrom file_descr gt string gt int gt int gt msg_flag list gt int sockaddr Receive data from an unconnected socket val send file_descr gt string gt int gt int gt msg_flag list gt int Send data over a connected socket val sendto file_descr gt string gt int gt int gt msg_flag list gt sockaddr gt int Send data over an unconnected socket Socket opt
508. stub code around the libz entry points The following command builds the Caml libraries zip cma and zip cmxa as well as the companion C libraries dllzip so and libzip a ocamlmklib o zip zip cmo zip cmx zipstubs o lz L usr local zlib If shared libraries are supported this performs the following commands ocamlc a o zip cma zip cmo dllib lzip cclib lzip cclib lz ccopt L usr local zlib ocamlopt a o zip cmxa zip cmx cclib lzip cclib lzip cclib lz ccopt L usr local zlib gcc shared o dllzip so zipstubs o lz L usr local zlib ar rc libzip a zipstubs o If shared libraries are not supported the following commands are performed instead Chapter 18 Interfacing C with Objective Caml 261 ocamlc a custom o zip cma zip cmo cclib lzip cclib lz ccopt L usr local zlib ocamlopt a o zip cmxa zip cmx lzip cclib lz ccopt L usr local zlib ar rc libzip a zipstubs o Instead of building simultaneously the bytecode library the native code library and the C libraries ocamlmklib can be called three times to build each separately Thus ocamlmklib o zip zip cmo lz L usr local zlib builds the bytecode library zip cma and ocamlmklib o zip zip cmx lz L usr local zlib builds the native code library zip cmxa and ocamlmklib o zip zipstubs o lz L usr local zlib builds the C libraries dllzip so and libzip a Notice that the support libraries 1z and the corresponding options L usr local zlib must
509. suffix Set the suffix used for generated man filenames Default is o like in List o 15 1 2 Merging of module information Information on a module can be extracted either from the mli or ml file or both depending on the files given on the command line When both mli and m1 files are given for the same module information extracted from these files is merged according to the following rules e Only elements values types classes declared in the m1i file are kept In other terms definitions from the m1 file that are not exported in the mli file are not documented e Descriptions of elements and descriptions in tags are handled as follows If a description for the same element or in the same tag of the same element is present in both files then the description of the m1 file is concatenated to the one in the m1i file if the corresponding m flag is given on the command line If a description is present in the m1 file and not in the mli file the m1 description is kept In either case all the information given in the m1i file is kept Chapter 15 The documentation generator ocamldoc 201 15 1 3 Coding rules The following rules must be respected in order to avoid name clashes resulting in cross reference errors e In a module there must not be two modules two module types or a module and a module type with the same name e In a module there must not be two classes two class types or a class and a class
510. t b gt bool gt a list gt b list gt bool Same as List exists 20 17 but for a two argument predicate Raise Invalid_argument if the two lists have different lengths val mem a gt a list gt bool mem a 1 is true if and only if a is equal to an element of 1 val memq a gt a list gt bool Same as List mem 20 17 but uses physical equality instead of structural equality to compare list elements List searching val find a gt bool gt a list gt a find p 1 returns the first element of the list 1 that satisfies the predicate p Raise Not_found if there is no value that satisfies p in the list 1 val filter a gt bool gt a list gt a list filter p 1 returns all the elements of the list 1 that satisfy the predicate p The order of the elements in the input list is preserved val find_all a gt bool gt a list gt a list find_all is another name for List filter 20 17 val partition a gt bool gt a list gt a list a list partition p 1 returns a pair of lists 11 12 where 11 is the list of all the elements of 1 that satisfy the predicate p and 12 is the list of all the elements of 1 that do not satisfy p The order of the elements in the input list is preserved 332 Association lists val assoc a gt a b list gt b assoc a 1 returns the value associated with key a in the list of pa
511. t 1 Node n1 Node n2 gt ASet compare n n2 end and ASet Set S with type elt A t Set Make A It can be given the following specification module rec A sig type t Leaf of string Node of ASet t val compare t gt t gt int end and ASet Set S with type elt A t This is an experimental extension of Objective Caml the class of recursive definitions accepted as well as its dynamic semantics are not final and subject to change in future releases Currently the compiler requires that all dependency cycles between the recursively defined module identifiers go through at least one safe module A module is safe if all value defini tions that it contains have function types ty gt ty Evaluation of a recursive module definition proceeds by building initial values for the safe modules involved binding all functional values to fun x gt raise Undefined_recursive_module The defining module expressions are then eval uated and the initial values for the safe modules are replaced by the values thus computed If a function component of a safe module is applied during this computation which corresponds to an ill founded recursive definition the Undefined_recursive_module exception is raised 140 Part III The Objective Caml tools 141 Chapter 8 Batch compilation ocamlc This chapter describes the Objective Caml batch compiler ocamlc which compiles Caml source files to bytecode object files
512. t 9 42 Now for a real symbolic processing we define the derivative of an expression with respect to a variable dv let rec deriv exp dv match exp with Const c gt Const 0 0 Var v gt if v dv then Const 1 0 else Const 0 0 Sum f g gt Sum deriv f dv deriv g dv Diff f g gt Diff deriv f dv deriv g dv Prod f g gt Sum Prod f deriv g dv Prod deriv f dv g Quot f g gt Quot Diff Prod deriv f dv g Prod f deriv g dv Prod g g 23 val deriv expression gt string gt expression lt fun gt deriv Quot Const 1 0 Var x x expression Quot Diff Prod Const 0 Var x Prod Const 1 Const 1 Prod Var x Var x 1 8 Pretty printing and parsing As shown in the examples above the internal representation also called abstract syntax of expres sions quickly becomes hard to read and write as the expressions get larger We need a printer and a parser to go back and forth between the abstract syntax and the concrete syntax which in the case of expressions is the familiar algebraic notation e g 2 x 1 For the printing function we take into account the usual precedence rules i e binds tighter than to avoid printing unnecessary parentheses To this end we maintain the current operator precedence and print parentheses around an operator only if its precedence is less than the current precedence let print_expr exp Local
513. t float gt int32 Return the internal representation of the given float according to the IEEE 754 floating point single format bit layout Bit 31 of the result represents the sign of the float bits 30 to 23 represent the biased exponent bits 22 to 0 represent the mantissa float_of_bits int32 gt float Return the floating point number whose internal representation according to the IEEE 754 floating point single format bit layout is the given int32 type t int32 val An alias for the type of 32 bit integers compare t gt t gt int The comparison function for 32 bit integers with the same specification as Pervasives compare Along with the type t this function compare allows the module Int32 to be passed as argument to the functors Set Make 20 28 and Map Make 20 18 Chapter 20 The standard library 323 20 14 Module Int64 64 bit integers This module provides operations on the type int64 of signed 64 bit integers Unlike the built in int type the type int64 is guaranteed to be exactly 64 bit wide on all platforms All arithmetic operations over int64 are taken modulo 264 Performance notice values of type int64 occupy more memory space than values of type int and arithmetic operations on int64 are generally slower than those on int Use int64 only when the application requires exact 64 bit arithmetic val zero int64 The 64 bit integer 0 val one int64 The 64 bit integer 1
514. t gt unit add_channel b ic n reads exactly n character from the input channel ic and stores them at the end of buffer b Raise End_of_file if the channel contains fewer than n characters val output_buffer Pervasives out_channel gt t gt unit output_buffer oc b writes the current contents of buffer b on the output channel oc 20 4 Module Callback Registering Caml values with the C run time This module allows Caml values to be registered with the C runtime under a symbolic name so that C code can later call back registered Caml functions or raise registered Caml exceptions val register string gt a gt unit Callback register n v registers the value v under the name n C code can later retrieve a handle to v by calling caml_named_value n Chapter 20 The standard library 295 val register_exception string gt exn gt unit Callback register_exception n exn registers the exception contained in the exception value exn under the name n C code can later retrieve a handle to the exception by calling caml_named_value n The exception value thus obtained is suitable for passign as first argument to raise_constant or raise_with_arg 20 5 Module Char Character operations val code char gt int Return the ASCII code of the argument val chr int gt char Return the character with the given ASCII code Raise Invalid_argument Char chr if the argument is outside the range 0 255 val escaped char
515. t newval val a ref gt a gt unit lt fun gt In some special cases you may need to store a polymorphic function in a data structure keeping its polymorphism Without user provided type annotations this is not allowed as polymorphism is only introduced on a global level However you can give explicitly polymorphic types to record fields type idref mutable id a a gt a type idref mutable id a a gt a let r id fun x gt x val r idref id lt fun gt let g s s id 1 s id true val g idref gt int bool lt fun gt r id lt fun x gt print_string called id n x unit 2 235 called id called id int bool 1 true 18 1 6 Exceptions Caml provides exceptions for signalling and handling exceptional conditions Exceptions can also be used as a general purpose non local control structure Exceptions are declared with the exception construct and signalled with the raise operator For instance the function below for taking the head of a list uses an exception to signal the case where an empty list is given exception Empty_list exception Empty_list let head 1 match 1 with gt raise Empty_list hd tl gt hd val head a list gt a lt fun gt head 1 2 int 1 head Exception Empty_list Exceptions are used throughout the standard lib
516. t select self self_init 346 send sendto service_entry 399 Set 352 set 290 314 B57 B59 361 B63 460 464 1265 467 set_all_formatter_output_functions 306 set_approx_printing set _binary_mode_ in 282 set_binary_mode_out 280 set_close_on_exec set_color set_ellipsis_text 485 set_error_when_null_denominator 414 set_floating_ precision set _font 433 set_formatter_out_channel set_formatter_output_functions 305 set_formatter_tag_functions 306 set_line_width set_margin 302 set_mark_tags 805 set_max_boxes set_max_indent 302 set _nonblock 384 set_normalize_ratio set_normalize_ratio_when_printing 414 set_print_tags 805 set_signal set_state set_tab set _tags 305 set_text_size set_window_title setattr_when 404 setgid 392 setitimer setsid 404 setsockopt setsockopt_float 398 setsockopt_int setsockopt_optint 398 setuid shift_left shift_right shift_right_logical shutdown 395 shutdown_command shutdown_connection 398 side 449 sigabrt 366 sigalrm 366 sigchld sigcont 366 sigfpe 366 sighup sigill 366 sigint 366 486 sigkil1 366 sign_big_int sign_num 409 signal 365 signal_behavior 365 sigpending 389 sigpipe 366 sigprocmask sigprocmask_command sigprof sigquit 366 sigsegv 366 sigstop sigsuspend 389 sigterm 366 sigtstp sigt
517. t char gt unit method sub int gt int gt a end Another constructor of the class string can be defined to return an uninitialized string of a given length class cstring n ostring String create n class cstring int gt ostring Here exposing the representation of strings is probably harmless We do could also hide the representation of strings as we hid the currency in the class money of section Stacks There is sometimes an alternative between using modules or classes for parametric data types Indeed there are situations when the two approaches are quite similar For instance a stack can be straightforwardly implemented as a class exception Empty exception Empty class a stack object val mutable 1 method push x O a list l lt x l 82 method pop match 1 with gt raise Empty a 1 gt 1 lt 1 a method clear 1 lt method length List length 1 end class a stack object val mutable 1 a list method clear unit method length int method pop a method push a gt unit end However writing a method for iterating over a stack is more problematic A method fold would have type b gt a gt b gt b gt b Here a is the parameter of the stack The parameter b is not related to the class a stack but to the argument that will be passed to the method fold A naive approach is to make
518. t string temp_file prefix suffix returns the name of a fresh temporary file in the temporary directory The base name of the temporary file is formed by concatenating prefix then a suitably chosen integer number then suffix The temporary file is created empty with permissions 00600 readable and writable only by the file owner The file is guaranteed to be different from any other file that existed when temp_file was called Under Unix the temporary directory is tmp by default if set the value of the environment variable TMPDIR is used instead Under Windows the name of the temporary directory is the value of the environment variable TEMP or C temp by default val open_temp_file mode Pervasives open_flag list gt string gt string gt string Pervasives out_channel Same as Filename temp_f ile 20 8 but returns both the name of a fresh temporary file and an output channel opened atomically on this file This function is more secure than temp_file there is no risk that the temporary file will be modified e g replaced by a symbolic link before the program opens it The optional argument mode is a list of additional flags to control the opening of the file It can contain one or several of Open_append Open_binary and Open_text The default is Open_text open in text mode val quote string gt string Return a quoted version of a file name suitable for use as one argument in a shell command line escaping all she
519. t be correctly located in the values printed by the toplevel loop The value path printer name must refer to one of the functions defined by the object files loaded using load_printer It cannot reference the functions of the program being debugged remove_printer printer name Remove the named function from the table of value printers 16 9 Miscellaneous commands list module beginning end List the source of module module from line number beginning to line number end By default 20 lines of the current module are displayed starting 10 lines before the current position source filename Read debugger commands from the script filename 16 10 Running the debugger under Emacs The most user friendly way to use the debugger is to run it under Emacs See the file emacs README in the distribution for information on how to load the Emacs Lisp files for Caml support The Caml debugger is started under Emacs by the command M x camldebug with argument the name of the executable file progname to debug Communication with the debugger takes place in an Emacs buffer named camldebug progname The editing and history facilities of Shell mode are available for interacting with the debugger In addition Emacs displays the source files containing the current event the current posi tion in the program execution and highlights the location of the event This display is updated synchronously with the debugger action The following bindings for th
520. t must therefore have type out_channel gt b gt unit and the second b The output produced by the function is therefore inserted in the output of fprintf at the current point t same as a but takes only one argument with type out_channel gt unit and apply it to outchan take no argument and flush the output take no argument and output one character The optional flags include left justify the output default is right justification 0 for numerical conversions pad with zeroes instead of spaces for numerical conversions prefix number with a sign if positive space for numerical conversions prefix number with a space if positive request an alternate formatting style for numbers The field widths are composed of an optional integer literal indicating the minimal width of the result possibly followed by a dot and another integer literal indicating how many digits follow the decimal point in the f e and E conversions For instance 46d prints an integer prefixing it with spaces to fill at least 6 characters and 4f prints a float with 4 344 fractional digits Each or both of the integer literals can also be specified as a in which case an extra integer argument is taken to specify the corresponding width or precision Warning if too few arguments are provided for instance because the printf function is partially applied the format is immediately printed up to the conversion
521. taken into account to compute the final hash value and therefore collisions are less likely to happen However hashing takes longer The parameters m and n govern the tradeoff between accuracy and speed 20 13 Module Int32 32 bit integers This module provides operations on the type int32 of signed 32 bit integers Unlike the built in int type the type int32 is guaranteed to be exactly 32 bit wide on all platforms All arithmetic operations over int32 are taken modulo Performance notice values of type int32 occupy more memory space than values of type int and arithmetic operations on int32 are generally slower than those on int Use int32 only when int gt int gt a gt int 232 the application requires exact 32 bit arithmetic val zero int32 The 32 bit integer 0 val one int32 The 32 bit integer 1 val minus_one int32 The 32 bit integer 1 val neg int32 gt int32 Unary negation val add int32 gt int32 Addition val sub int32 gt int32 Subtraction val mul int32 gt int32 Multiplication val div int32 gt int32 gt gt gt gt int32 int32 int32 int32 Chapter 20 The standard library 321 val val val val val val val val val val val val Integer division Raise Division_by_zero if the second argument is zero This division rounds the real quotient of its arguments towards zero as specified fo
522. ted by juxtaposition of possibly labeled expressions Evaluation works as for expression application Class function The expression fun label name pattern gt class expr evaluates to a function from values to classes When this function is applied to a value v this value is matched against the pattern pattern and the result is the result of the evaluation of class expr in the extended environment Conversion from functions with default values to functions with patterns only works identically for class functions as for normal functions The expression fun parameter parameter gt class expr Chapter 6 The Objective Caml language 123 is a short form for fun parameter gt fun parameter gt expr Local definitions The let and let rec constructs bind value names locally as for the core language expressions Class body The expression object pattern typexpr class field end denotes a class body This is the prototype for an object it lists the instance variables and methods of an objet of this class A class body is a class value it is not evaluated at once Rather its components are evaluated each time an object is created In a class body the pattern pattern typexpr is matched against self therefore provinding a binding for self and self type Self can only be used in method and initializers Self type cannot be a closed object type so that the class remains extensible Inheritance
523. ted only if the bytecode executable contains debugging information i e was compiled and linked with the g option to ocamlc set This is equivalent to setting the b flag in the OCAMLRUNPARAM environment variable see below I dir Search the directory dir for dynamically loaded libraries in addition to the standard search path see section 10 3 v Direct the memory manager to print some progress messages on standard error This is equivalent to setting v 63 in the OCAMLRUNPARAM environment variable see below The following environment variables are also consulted CAML_LD_LIBRARY_PATH Additional directories to search for dynamically loaded libraries see section 10 3 OCAMLLIB The directory containing the Objective Caml standard library If OCAMLLIB is not set CAMLLIB will be used instead Used to locate the 1d conf configuration file for dynamic loading see section 10 3 If not set default to the library directory specified when compiling Objective Caml OCAMLRUNPARAM Set the runtime system options and garbage collection parameters If OCAMLRUNPARAM is not set CAMLRUNPARAM will be used instead This variable must be a sequence of parameter specifications A parameter specification is an option letter followed by an sign a decimal number or an hexadecimal number prefixed by Ox and an optional multiplier There are nine options six of which correspond to the fields of the control record documented in section b
524. ter Notes e the scanning indications introduce slight differences in the syntax of Scanf format strings compared to those used by the Printf module However scanning indications are similar to those of the Format module hence when producing formatted text to be scanned by Scanf bscanf it is wise to use printing functions from Format or if you need to use functions from Printf banish or carefully double check the format strings that contain characters e in addition to relevant digits _ characters may appear inside numbers this is reminiscent to the usual Caml conventions If stricter scanning is desired use the range conversion facility instead of the number conversions e the scanf facility is not intended for heavy duty lexical analysis and parsing If it appears not expressive enough for your needs several alternative exists regular expressions module Str stream parsers ocamllex generated lexers ocamlyacc generated parsers val fscanf Pervasives in_channel gt Ca Scanning scanbuf b Pervasives format gt a gt b Same as Scanf bscanf 20 27 but inputs from the given channel Warning since all scanning functions operate from a scanning buffer be aware that each fscanf invocation must allocate a new fresh scanning buffer unless careful use of partial evaluation in the program Hence there are chances that some characters seem to be skipped in fact they are pending in the previous
525. ter 12 Lexer and parser generators ocamllex ocamlyacc 183 At run time the ocamlyacc generated parser can be debugged by setting the p option in the OCAMLRUNPARAM environment variable see section 10 2 This causes the pushdown automaton executing the parser to print a trace of its action tokens shifted rules reduced etc The trace mentions rule numbers and state numbers that can be interpreted by looking at the file gram mar output generated by ocamlyacc v 12 6 A complete example The all time favorite a desk calculator This program reads arithmetic expressions on standard input one per line and prints their values Here is the grammar definition File parser mly token lt int gt INT token PLUS MINUS TIMES DIV token LPAREN RPAREN token EOL left PLUS MINUS lowest precedence left TIMES DIV medium precedence nonassoc UMINUS highest precedence start main the entry point type lt int gt main Ah main expr EOL 1 expr INT 1 LPAREN expr RPAREN 2 expr PLUS expr 1 3 expr MINUS expr 1 3 expr TIMES expr 1 3 expr DIV expr 1 3 MINUS expr prec UMINUS 2 Here is the definition for the corresponding lexer File lexer ml1l open Parser The type token is defined in parser mli exception Eof rule token parse t2 token lexbuf skip blanks P p EOL 0 9 as 1lxm INT int_o
526. ter 20 The standard library 367 Continue val sigstop int Stop val sigtstp int Interactive stop val sigttin int Terminal read from background process val sigttou int Terminal write from background process val sigvtalrm int Timeout in virtual time val sigprof int Profiling interrupt exception Break Exception raised on interactive interrupt if Sys catch_break 20 34 is on val catch_break bool gt unit catch_break governs whether interactive interrupt ctrl C terminates the program or raises the Break exception Call catch_break true to enable raising Break and catch_break false to let the system terminate the program on user interrupt val ocaml_version string ocaml_version is the version of Objective Caml It is a string of the form major minor patchlevel tadditional info Where major minor and patchlevel are integers and additional info is an arbitrary string The patchlevel and additional info parts may be absent 20 35 Module Weak Arrays of weak pointers and hash tables of weak pointers Low level functions type at 368 val val val val val val val The type of arrays of weak pointers weak arrays A weak pointer is a value that the garbage collector may erase at any time A weak pointer is said to be full if it points to a value empty if the value was erased by the GC Note that weak arrays cannot be marshaled using Pervasives output_valu
527. tform max_int nativeint The greatest representable native integer either 2 1 on a 32 bit platform or 263 1 ona 64 bit platform min_int nativeint 281 The greatest representable native integer either on a 32 bit platform or 26 on a 64 bit platform logand nativeint gt nativeint gt nativeint Bitwise logical and logor nativeint gt nativeint gt nativeint Bitwise logical or logxor nativeint gt nativeint gt nativeint Bitwise logical exclusive or lognot nativeint gt nativeint Bitwise logical negation shift_left nativeint gt int gt nativeint Nativeint shift_left x y shifts x to the left by y bits The result is unspecified if y lt 0 or y gt bitsize where bitsize is 32 on a 32 bit platform and 64 on a 64 bit platform shift_right nativeint gt int gt nativeint Nativeint shift_right x y shifts x to the right by y bits This is an arithmetic shift the sign bit of x is replicated and inserted in the vacated bits The result is unspecified if y lt 0 or y gt bitsize shift_right_logical nativeint gt int gt nativeint Nativeint shift_right_logical x y shifts x to the right by y bits This is a logical shift zeroes are inserted in the vacated bits regardless of the sign of x The result is unspecified if y lt Oor y gt bitsize of_int int gt nativeint Convert the given integer type int to a native integer type nativeint
528. th respect to sharing and functional values If flags does not contain Marshal No_sharing circularities and sharing inside the value v are detected and preserved in the sequence of bytes produced In particular this guarantees that marshaling always terminates Sharing between values marshaled by successive calls to Marshal to_channel is not detected though If flags contains Marshal No_sharing sharing is ignored This results in faster marshaling if v contains no shared substructures but may cause slower marshaling and larger byte representations if v actually contains sharing or even non termination if v contains cycles If flags does not contain Marshal Closures marshaling fails when it encounters a functional value inside v only pure data structures containing neither functions nor objects can safely be transmitted between different programs If flags contains Marshal Closures functional values will be marshaled as a position in the code of the program In this case the output of marshaling can only be read back in processes that run exactly the same program with exactly the same compiled code This is checked at un marshaling time using an MD5 digest of the code transmitted along with the code position val to_string a gt extern_flags list gt string Marshal to_string v flags returns a string containing the representation of v as a sequence of bytes The flags argument has the same meaning as for Marshal to_ch
529. th a more complete example representative of the use of Caml for symbolic processing formal manipulations of arithmetic expressions containing variables The following variant type describes the expressions we shall manipulate type expression Quot of expression expression el e2 Const of float Var of string Sum of expression expression e1 e2 Diff of expression expression e1 e2 Prod of expression expression el e2 29 type expression Const of float Var of string Sum of expression expression Diff of expression expression Prod of expression expression Quot of expression expression We first define a function to evaluate an expression given an environment that maps variable names to their values For simplicity the environment is represented as an association list exception Unbound_variable of string exception Unbound_variable of string let rec eval env exp match exp with Const c gt c Var v gt try List assoc v env with Not_found gt raise Unbound_variable v Sum f g gt eval env f eval env g Diff f g gt eval env f eval env g 20 Prod f g gt eval env f eval env g Quot f g gt eval env f eval env g val eval string float list gt expression gt float lt fun gt eval x 1 0 y 3 14 Prod Sum Var x Const 2 0 Var y floa
530. thdraw c balance val close lt balance a withdraw a gt b gt gt b lt fun gt Of course this applies to all sorts of accounts Finally we gather several versions of the account into a module Account abstracted over some currency let today 01 01 2000 an approximation module Account M MONEY struct type m M c let m new M c let zero m 0 Chapter 5 Advanced examples with classes and modules class bank object self val mutable balance zero method balance balance val mutable history method private trace x history lt x history method deposit x self trace Deposit x if zero leq x then balance lt balance plus x else raise Invalid_argument deposit method withdraw x if x leq balance then else zero method history List rev history end class type client_view object method deposit m gt unit method history m operation list method withdraw m gt m method balance m end class virtual check_client x let y if m 100 leq x then x else raise Failure Insufficient initial deposit in object self initializer self deposit y end module Client B sig class bank client_view end struct class account x client_view object inherit B bank inherit check_client x end let discount x let c new account x in if today lt 1998 10 30 then c deposit m 100 c end end HHH HH HHH HHH HH
531. the boolean false true the boolean true O the unit value the empty list The current implementation limits each variant type to have at most 246 non constant con structors 6 2 6 Polymorphic variants Polymorphic variants are an alternate form of variant values not belonging explicitly to a predefined variant type and following specific typing rules They can be either constant written tag name or non constant written tag name v 6 2 7 Functions Functional values are mappings from values to values 6 2 8 Objects Objects are composed of a hidden internal state which is a record of instance variables and a set of methods for accessing and modifying these variables The structure of an object is described by the toplevel class that created it 6 3 Names Identifiers are used to give names to several classes of language objects and refer to these objects by name later Chapter 6 The Objective Caml language 97 e value names syntactic class value name e value constructors and exception constructors class constr name e labels label name e variant tags tag name e type constructors typeconstr name e record fields field name e class names class name e method names method name e instance variable names inst var name e module names module name e module type names modtype name These eleven name spaces are distinguished both by the context and by the
532. the keywords must appear in this order method private virtual 3 7 Class interfaces Class interfaces are inferred from class definitions They may also be defined directly and used to restrict the type of a class Like class declarations they also define a new type abbreviation class type restricted_point_type object method get_x int method bump unit end class type restricted_point_type object method bump unit method get_x int end fun x restricted_point_type gt x restricted_point_type gt restricted_point_type lt fun gt In addition to program documentation class interfaces can be used to constrain the type of a class Both instance variables and concrete private methods can be hidden by a class type constraint Public and virtual methods however cannot class restricted_point x restricted_point x restricted_point_type class restricted_point int gt restricted_point_type Or equivalently class restricted_point restricted_point int gt restricted_point_type class restricted_point int gt restricted_point_type The interface of a class can also be specified in a module signature and used to restrict the inferred signature of a module module type POINT sig class restricted_point int gt object method get_x int method bump unit end 42 end module type POINT sig class restricted_point int
533. the x coordinate class point fun x_init gt object val mutable x x_init method get_x x method move d x lt x d end class point int gt object val mutable x int method get_x int method move int gt unit end Like in function definitions the definition above can be abbreviated as class point x_init object val mutable x x_init method get_x x method move d x lt x d end class point int gt object val mutable x int method get_x int method move int gt unit end An instance of the class point is now a function that expects an initial parameter to create a point object new point int gt point lt fun gt let p new point 7 val p point lt obj gt Chapter 3 Objects in Caml 35 The parameter x_init is of course visible in the whole body of the definition including methods For instance the method get_offset in the class below returns the position of the object relative to its initial position class point x_init object val mutable x x_init method get_x x method get_offset x x_init method move d x lt x d H H HF FF end class point int gt object val mutable x int method get_offset int method get_x int method move int gt unit end Expressions can be evaluated and bound before defining the object body of the class This is useful to enforce invariants For i
534. ther box if this is a sub module or display the signature for this identifier below Signatures are clickable Double clicking with the left mouse button on an identifier in a signature brings you to its signature A single click on the right button pops up a menu displaying To avoid combinatorial explosion of the search space optional arguments in the actual type are ignored in the actual if 1 there are too many of them and 2 they do not appear explicitly in the pattern Chapter 14 The browser editor ocamlbrowser 193 the type declaration for the selected identifier Its title when selectable also brings you to its signature At the bottom a series of buttons depending on the context e Detach copies the currently displayed signature in a new window to keep it e Impl and Intf bring you to the implementation or interface of the currently displayed signa ture if it is available Control S lets you search a string in the signature 14 4 File editor You can edit files with it if you re not yet used to emacs Otherwise you can use it as a browser making occasional corrections The Edit menu contains commands for jump C g search C s and sending the current phrase or selection if some text is selected to a sub shell M x For this last option you may choose the shell via a dialog Essential functions are in the Compiler menu e Preferences opens a dialog to set internals of the editor and type checker e
535. tin sigttou sigusr1 366 sigusr2 366 sigvtalrm sin single_write 879 singleton 853 sinh 273 size 839 size_x size_y sleep slice_left slice_left_1 slice_left_2 slice_right slice_right_1 68 slice_right_2 snd 276 sockaddr socket socket_bool_option socket_domain socket_float_option socket_int_option socket_optint_option socket _type socketpair 894 Sort 355 sound 436 spec split B32 355 B53 TT split_delin split_result sprintf sqrt sqrt_big_int square_big_int square_num 408 sscanf stable_sort 292 333 357 358 Stack Stack_overflow stat State stats status std_formatter stdbuf stderr 276 378 stdib stdin 276 378 StdLabels 356 stdout Str str_formatter Stream String string string_after string_before 419 string_match string_of_big_int 413 string_of_bool string_of_float string_of_format string_of_inet_addr 893 string_of_int string_of_num string_partial_match 417 sub 297 P93 P96 20 B23 B38 B57 B59 B62 163 INDEX TO THE LIBRARY sub_big_int I sub_left sub_nun sub_right subset 353 substitute_first substring succ 270 B21 B23 B39 succ_big_int succ_num symbol_end symbol_end_pos 841 symbol_start symbol_start_pos 341 symlink sync synchronize Sys Sys_blocked_io Sys_error system t 293 295 319 3221 32
536. ting function can then print any regular material to the formatter so that this material is enqueued as usual in the formatter queue for further line breaking computation Marking a tag means to output an arbitrary string the tag marker directly into the output device of the formatter Hence the formatter specific tag marking function must return the tag marker string associated to its tag argument Being flushed directly into the output device of the formatter tag marker strings are not considered as part of the printing material that drives line breaking in other words the length of the strings corresponding to tag markers is considered as zero for line breaking In addition advanced users may take advantage of the specificity of tag markers to be precisely output when the pretty printer has already decided where to break the lines and precisely when the queue is flushed into the output device In the spirit of HTML tags the default tag marking functions output tags enclosed in lt and gt hence the opening marker of tag t is lt t gt and the closing marker lt t gt Default tag printing functions just do nothing Tag marking and tag printing functions are user definable and can be set by calling set_formatter_tag_functions val open_tag tag gt unit open_tag t opens the tag named t the print_open_tag function of the formatter is called with t as argument the tag marker mark_open_tag t will be
537. tion the system infers their types from their usage in the function Notice also that integers and floating point numbers are distinct types with distinct operators and operate on integers but and operate on floats 1 0 23 This expression has type float but is here used with type int 11 12 Recursive functions are defined with the let rec binding let rec fib n if n lt 2 then 1 else fib n 1 fib n 2 val fib int gt int lt fun gt fib 10 int 89 1 2 Data types In addition to integers and floating point numbers Caml offers the usual basic data types booleans characters and character strings 1 lt 2 false bool false a s char a Hello world string Hello world Predefined data structures include tuples arrays and lists General mechanisms for defining your own data structures are also provided They will be covered in more details later for now we concentrate on lists Lists are either given in extension as a bracketed list of semicolon separated elements or built from the empty list pronounce nil by adding elements in front using the cons operator let 1 is a tale told etc val 1 string list is a tale told etc Life l string list Life is a tale told etc As with all other Caml data structures lists do not need to be exp
538. tion of the error It consults the TERM variable to determines the type of output terminal and look up its capabilities in the terminal database HOME Directory where the ocamlinit file is searched 9 2 Toplevel directives The following directives control the toplevel behavior load files in memory and trace program execution Note all directives start with a sharp symbol This must be typed before the directive and must not be confused with the prompt displayed by the interactive loop For instance typing quit will exit the toplevel loop but typing quit will result in an unbound value quit error quit Exit the toplevel loop and terminate the ocam1 command labels bool Ignore labels in function types if argument is false or switch back to default behaviour commuting style if argument is true warnings warning list Enable or disable warnings according to the argument directory dir name Add the given directory to the list of directories searched for source and compiled files cd dir name Change the current working directory load file name Load in memory a bytecode object file cmo file produced by the batch compiler ocamlc use file name Read compile and execute source phrases from the given file This is textual inclusion phrases are processed just as if they were typed on standard input The reading of the file stops at the first error encountered instal
539. to extract See Bigarray Genarray slice_left 29 1 for more details Array2 slice_left applies only to arrays with C layout val slice_right Ca b Bigarray fortran_layout t gt int gt a b Bigarray fortran_layout Bigarray Array1 t Extract a column one dimensional slice of the given two dimensional big array The integer parameter is the index of the column to extract See Bigarray Genarray slice_right 29 1 for more details Array2 slice_right applies only to arrays with Fortran layout val blit a b c t gt Ca b c t gt unit Copy the first big array to the second big array See Bigarray Genarray blit 29 1 for more details val fill Ca b c t gt a gt unit Fill the given big array with the given value See Bigarray Genarray fill for more details val of_array Ca b Bigarray kind gt c Bigarray layout gt a array array gt a b c t Build a two dimensional big array initialized from the given array of arrays val map_file Unix file_descr gt Ca b Bigarray kind gt c Bigarray layout gt bool gt int gt int gt a b c t Memory mapping of a file as a two dimensional big array See Bigarray Genarray map_file for more details end Two dimensional arrays The Array2 structure provides operations similar to those of Bigarray Genarray 29 1 but specialized to the case of two dimensional arrays Chapter 29 The b
540. top of the screen and angles are measured counterclockwise in degrees Drawing is clipped to the screen y Screen pixel at x y x size_x 25 1 Module Graphics Machine independent graphics primitives exception Graphic_failure of string Raised by the functions below when they encounter an error Initializations val open_graph string gt unit Show the graphics window or switch the screen to graphic mode The graphics window is cleared and the current point is set to 0 0 The string argument is used to pass optional information on the desired graphics mode the graphics window size and so on Its interpretation is implementation dependent If the empty string is given a sensible default is selected val close_graph unit gt unit Delete the graphics window or switch the screen back to text mode val set_window_title string gt unit Set the title of the graphics window val clear_graph unit gt unit Chapter 25 The graphics library 431 Erase the graphics window val size_x unit gt int See Graphics size_y i val size_y unit gt int Return the size of the graphics window Coordinates of the screen pixels range over 0 size_x land0O size_y 1 Drawings outside of this rectangle are clipped without causing an error The origin 0 0 is at the lower left corner Colors type color int A color is specified by its R G B components Each component is in the ran
541. tors as explained in section 15 3 In this chapter we use the word element to refer to any of the following parts of an OCaml source file a type declaration a value a module an exception a module type a type constructor a record field a class a class type a class method a class value or a class inheritance clause 15 1 Usage 15 1 1 Invocation OCamldoc is invoked via the command ocamldoc as follows ocamldoc options sourcefiles Options for choosing the output format The following options determine the format for the generated documentation html Generate documentation in HTML default format The generated HTML pages are stored in the current directory or in the directory specified with the d option You can customize the style of the generated pages by editing the generated style css file or by providing your own style sheet using option css style The file style css is not generated if it already exists latex Generate documentation in IATFX default format The generated ATFX document is saved in 195 196 file ocamldoc out or in the file specified with the o option The document uses the style file ocamldoc sty This file is generated when using the latex option if it does not already exist You can change this file to customize the style of your BTE X documentation texi Generate documentation in TeXinfo default format The generated ATEX document is saved in file ocamldoc out or in the file spec
542. tract outside of the module 62 Chapter 4 Labels and variants Chapter written by Jacques Garrigue This chapter gives an overview of the new features in Objective Caml 3 labels and polymorphic variants 4 1 Labels If you have a look at modules ending in Labels in the standard library you will see that function types have annotations you did not have in the functions you defined yourself ListLabels map f Ca gt b gt a list gt b list lt fun gt StringLabels sub The files usr local bin ocaml and usr local lib ocaml stringLabels cmi make inconsistent assumptions over interface StringLabels Such annotations of the form name are called labels They are meant to document the code allow more checking and give more flexibility to function application You can give such names to arguments in your programs by prefixing them with a tilde let f x y x ys val f x int gt y int gt int lt fun gt let x 3 and y 2 in f x y int 1 When you want to use distinct names for the variable and the label appearing in the type you can use a naming label of the form name This also applies when the argument is not a variable let f x x1 y yl x1 yl val f x int gt y int gt int lt fun gt f x 3 7y 2 int 1 63 64 Labels obey the same rules as other identifiers in Caml that is you cannot use a reserved keyword like
543. tran layout can be given as 1 Genarray map_file then determines the major dimension from the size of the file The file must contain an integral number of sub arrays as determined by the non major dimensions otherwise Failure is raised If all dimensions of the big array are given the file size is matched against the size of the big array If the file is larger than the big array only the initial portion of the file is mapped to the big array If the file is smaller than the big array the file is automatically grown to the size of the big array This requires write permissions on fd One dimensional arrays module Array1 sig type Ca b c t val The type of one dimensional big arrays whose elements have Caml type a representation kind b and memory layout c create a b Bigarray kind gt gt c Bigarray layout gt int gt a b c t val val val val Arrayl create kind layout dim returns a new bigarray of one dimension whose size is dim kind and layout determine the array element kind and the array layout as described for Genarray create dim a b c t gt int Return the size dimension of the given one dimensional big array kind a b c t gt Ca b Bigarray kind Return the kind of the given big array layout a b c t gt c Bigarray layout Return the layout of the given big array get Ca b c t gt int gt
544. troduction to Objective Caml Chapter 1 The core language This part of the manual is a tutorial introduction to the Objective Caml language A good famil iarity with programming in a conventional languages say Pascal or C is assumed but no prior exposure to functional languages is required The present chapter introduces the core language Chapter 3 deals with the object oriented features and chapter 2 with the module system 1 1 Basics For this overview of Caml we use the interactive system which is started by running ocaml1 from the Unix shell or by launching the OCamlwin exe application under Windows This tutorial is presented as the transcript of a session with the interactive system lines starting with represent user input the system responses are printed below without a leading Under the interactive system the user types Caml phrases terminated by in response to the prompt and the system compiles them on the fly executes them and prints the outcome of evaluation Phrases are either simple expressions or let definitions of identifiers either values or functions 1 2 3 int 7 let pi 4 0 atan 1 0 val pi float 3 14159265358979312 let square x X X val square float gt float lt fun gt square sin pi square cos pi float 1 The Caml system computes both the value and the type for each phrase Even function parameters need no explicit type declara
545. ts displayed when approx_printing is on Initially 12 Chapter 23 The str library regular expressions and string processing The str library provides high level string processing functions some based on regular expressions It is intended to support the kind of file processing that is usually performed with scripting languages such as awk perl or sed Programs that use the str library must be linked as follows ocamlc other options str cma other files ocamlopt other options str cmxa other files For interactive use of the str library do ocamlmktop o mytop str cma mytop or if dynamic linking of C libraries is supported on your platform start ocaml and type 1load Str cma 23 1 Module Str Regular expressions and high level string pro cessing Regular expressions type regexp The type of compiled regular expressions val regexp string gt regexp Compile a regular expression The following constructs are recognized e Matches any character except newline e postfix Matches the preceding expression zero one or several times 415 416 val val val val postfix Matches the preceding expression one or several times postfix Matches the preceding expression once or not at all e Character set Ranges are denoted with as in a z An initial as in 70 9 complements the set To include a character in a set make it the first character of the set To include a ch
546. ts have different lengths Not tail recursive Sorting val sort a gt a gt int gt a list gt a list Chapter 20 The standard library 333 Sort a list in increasing order according to a comparison function The comparison function must return 0 if its arguments compare as equal a positive integer if the first is greater and a negative integer if the first is smaller see Array sort for a complete specification For example Pervasives compare 19 2 is a suitable comparison function The resulting list is sorted in increasing order List sort is guaranteed to run in constant heap space in addition to the size of the result list and logarithmic stack space The current implementation uses Merge Sort It runs in constant heap space and logarithmic stack space val stable_sort a gt a gt int gt a list gt a list Same as List sort 20 17 but the sorting algorithm is guaranteed to be stable i e elements that compare equal are kept in their original order The current implementation uses Merge Sort It runs in constant heap space and logarithmic stack space val fast_sort a gt a gt int gt a list gt a list Same as List sort 20 17 or List stable_sort 20 17 whichever is faster on typical input val merge a gt a gt int gt a list gt a list gt a list Merge two lists Assuming that 11 and 12 are sorted according to the comparison fun
547. turns a scanning buffer with the given function as its reading method When scanning needs one more character the given function is called When the function has no more character to provide it must signal an end of input condition by raising the exception End_of_file from_channel Pervasives in_channel gt scanbuf Scanning from_channel inchan returns a scanning buffer which reads one character at a time from the input channel inchan starting at the current reading position end_of_input scanbuf gt bool Scanning end_of_input scanbuf tests the end of input condition of the given buffer Chapter 20 The standard library 349 val beginning of_input scanbuf gt bool Scanning beginning _of_input scanbuf tests the beginning of input condition of the given buffer end Scanning buffers exception Scan_failure of string The exception that formatted input functions raise when the input cannot be read according to the given format val bscanf Scanning scanbuf gt Ca Scanning scanbuf b Pervasives format gt a gt b bscanf ib format f reads tokens from the scanning buffer ib according to the format string format converts these tokens to values and applies the function f to these values The result of this application of f is the result of the whole construct For instance if p is the function fun s i gt i 1 then Scanf sscanf x 1 s i p returns 2 Raise Scanf Scan_failure if the gi
548. uffer Long_val offset Long_val length Here Val_long Long_val and so on are conversion macros for the type value that will be described later The CAMLprim macro expands to the required compiler directives to ensure that the function following it is exported and accessible from Caml The hard work is performed by the function getblock which is declared as long getblock struct channel channel char p long n To write C code that operates on Objective Caml values the following include files are provided Include file Provides caml mlvalues h definition of the value type and conversion macros caml alloc h allocation functions to create structured Caml objects caml memory h miscellaneous memory related functions and macros for GC interface in place modification of structures etc caml fail h functions for raising exceptions see section caml callback h callback from C to Caml see section 18 7 caml custom h operations on custom blocks see section 18 9 caml intext h operations for writing user defined serialization and deserialization func tions for custom blocks see section 18 9 These files reside in the cam1 subdirectory of the Objective Caml standard library directory usually usr local lib ocam1 234 18 1 3 Statically linking C code with Caml code The Objective Caml runtime system comprises three main parts the bytecode interpreter the memory manager and a
549. ule where n is the integer parameter to rhs_start and rhs_end n is 1 for the leftmost item rhs_end int gt int See Parsing rhs_start 20 22 symbol_start_pos unit gt Lexing position Same as symbol_start but return a position instead of an offset symbol_end_pos unit gt Lexing position Same as symbol_end but return a position instead of an offset rhs_start_pos int gt Lexing position Same as rhs_start but return a position instead of an offset rhs_end_pos int gt Lexing position Same as rhs_end but return a position instead of an offset clear_parser unit gt unit Empty the parser stack Call it just after a parsing function has returned to remove all pointers from the parser stack to structures that were built by semantic actions during parsing This is optional but lowers the memory requirements of the programs exception Parse_error Raised when a parser encounters a syntax error Can also be raised from the action part of a grammar rule to initiate error recovery 342 20 23 Module Printexc Facilities for printing exceptions val to_string exn gt string Printexc to_string e returns a string representation of the exception e val print a gt b gt a gt b Printexc print fn x applies fn to x and returns the result If the evaluation of fn x raises any exception the name of the exception is printed on standard error output and the exception is raised
550. uments of type value and return a result of type value The type value is the type of the representations for Caml values It encodes objects of several base types integers floating point numbers strings as well as Caml data structures The type value and the associated conversion functions and macros are described in details below For instance here is the declaration for the C function implementing the input primitive CAMLprim value input value channel value buffer value offset value length When the primitive function is applied in a Caml program the C function is called with the values of the expressions to which the primitive is applied as arguments The value returned by the function is passed back to the Caml program as the result of the function application User primitives with arity greater than 5 should be implemented by two C functions The first function to be used in conjunction with the bytecode compiler ocamlc receives two arguments a pointer to an array of Caml values the values for the arguments and an integer which is the number of arguments provided The other function to be used in conjunction with the native code compiler ocamlopt takes its arguments directly For instance here are the two C functions for the 7 argument primitive Nat add_nat CAMLprim value add_nat_native value nati value ofsi value lent value nat2 value ofs2 value len2 value carry_in CAMLprim value add_nat_bytecod
551. unctor Client so that client accounts can still be build after a possible specialization of the bank The functor Client may remain unchanged and be passed the new definition to initialize a client s view of the extended account module Investment_account M MONEY struct type m M c module A Account M class bank object inherit A bank as super method deposit x if new M c 1000 leq x then print_string Would you like to invest super deposit x end module Client A Client end The functor Client may also be redefined when some new features of the account can be given to the client module Internet_account M MONEY struct type m M c module A Account M class bank Chapter 5 Advanced examples with classes and modules 79 object inherit A bank method mail s print_string s end class type client_view object method deposit m gt unit method history m operation list method withdraw m gt m method balance m method mail string gt unit end module Client B sig class bank client_view end struct class account x client_view object inherit B bank inherit A check_client x end end end HH HH HH HH HH HH FH OH FH OH FH FH OH FH OF OF 5 2 Simple modules as classes One may wonder whether it is possible to treat primitive types such as integers and strings as objects Although this is usually unint
552. unix cma mytop or if dynamic linking of C libraries is supported on your platform start ocaml and type 1load unix cma Windows A fairly complete emulation of the Unix system calls is provided in the Windows version of Objective Caml The end of this chapter gives more information on the functions that are not supported under Windows 21 1 Module Unix Interface to the Unix system Error report type error E2BIG Argument list too long EACCES Permission denied 371 372 EAGAIN Resource temporarily unavailable try again EBADF Bad file descriptor EBUSY Resource unavailable ECHILD No child process EDEADLK Resource deadlock would occur EDOM Domain error for math functions etc EEXIST File exists EFAULT Bad address EFBIG File too large EINTR Function interrupted by signal EINVAL Invalid argument EIO Hardware I O error EISDIR Is a directory EMFILE Too many open files by the process EMLINK Too many links ENAMETOOLONG Filename too long ENFILE Too many open files in the system Chapter 21 The unix library Unix system calls ENOQDEV No such device ENOENT No such file or directory ENOEXEC Not an executable file ENOLCK No locks available ENOMEM Not enough memory ENOSPC No space left on device ENOSYS Function not supported ENOTDIR Not a directory ENOTEMPTY Directory not empty ENOTTY Inappropriate I O control operation ENXIO No such device or
553. urn the string representation of a floating point number val float_of_string string gt float Convert the given string to a float Raise Failure float_of_string if the given string is not a valid representation of a float Pair operations val fst a b gt a Return the first component of a pair val snd a b gt b Return the second component of a pair List operations More list operations are provided in module List 20 17 val a list gt a list gt a list List concatenation Input output type in_channel The type of input channel type out_channel The type of output channel val stdin in_channel The standard input for the process val stdout out_channel The standard output for the process val stderr out_channel The standard error ouput for the process Chapter 19 The core library 277 Output functions on standard output val print_char char gt unit Print a character on standard output val print_string string gt unit Print a string on standard output val print_int int gt unit Print an integer in decimal on standard output val print_float float gt unit Print a floating point number in decimal on standard output val print_endline string gt unit Print a string followed by a newline character on standard output and flush standard output val print_newline unit gt unit Print a newline c
554. urrent directory false if it is absolute i e in Unix starts with is_implicit string gt bool Return true if the file name is relative and does not start with an explicit reference to the current directory or in Unix false if it starts with an explicit reference to the root directory or the current directory check_suffix string gt string gt bool check_suffix name suff returns true if the filename name ends with the suffix suff chop_suffix string gt string gt string chop_suffix name suff removes the suffix suff from the filename name The behavior is undefined if name does not end with the suffix suff chop_extension string gt string Return the given file name without its extension The extension is the shortest suffix starting with a period and not including a directory separator xyz for instance Raise Invalid_argument if the given name does not contain an extension basename string gt string Split a file name into directory name base file name concat dirname name basename name returns a file name which is equivalent to name Moreover after setting the current directory to dirname name with Sys chdir 20 34 references to basename name which is a relative file name designate the same file as name before the call to Sys chdir 20 34 Chapter 20 The standard library 299 val dirname string gt string See Filename basename val temp_file string gt string g
555. us providing implementations for the specifications expressed in class types 122 class expr class path typexpr typexpr class path class expr class expr class type class expr argument fun parameter gt class expr let rec let binding and let binding in class expr object pattern typexpr class field end class field inherit class expr as value name val mutable inst var name typexpr expr method private method name parameter typexpr expr method private method name poly typexpr expr method private virtual method name poly typexpr constraint typexpr typexpr initializer expr Simple class expressions The expression class path evaluates to the class bound to the name class path Similarly the ex pression typexpr typexpr class path evaluates to the parametric class bound to the name class path in which type parameters have been instanciated to respectively typexpr typexpr The expression class expr evaluates to the same module as class expr The expression class expr class type checks that class type match the type of class expr that is that the implementation class expr meets the type specification class type The whole expression evaluates to the same class as class expr except that all components not specified in class type are hidden and can no longer be accessed Class application Class application is deno
556. use of the graphics library do ocamlmktop o mytop graphics cma mytop or if dynamic linking of C libraries is supported on your platform start ocaml and type load graphics cma Here are the graphics mode specifications supported by open_graph on the X11 implementa tion of this library the argument to open_graph has the format display name geometry where display name is the name of the X windows display to connect to and geometry is a standard X windows geometry specification The two components are separated by a space Either can be omitted or both Examples open_graph foo 0 connects to the display foo 0 and creates a window with the default geometry open_graph foo 0 300x100 50 0 connects to the display foo 0 and creates a window 300 pixels wide by 100 pixels tall at location 50 0 open_graph 300x100 50 0 connects to the default display and creates a window 300 pixels wide by 100 pixels tall at location 50 0 open_graph connects to the default display and creates a window with the default geometry 429 430 Windows This library is available both for standalone compiled programs and under the toplevel ap plication ocamlwin exe For the latter this library must be loaded in core by typing load graphics cma The screen coordinates are interpreted as shown in the figure below Notice that the coordinate system used is the same as in mathematics y increases from the bottom of the screen to the
557. ut blanks For instance Pervasives M2 M3 inv merge ml mli Inverse implementations and interfaces when merging All elements in implementation files Chapter 15 The documentation generator ocamldoc 197 are kept and the m option indicates which parts of the comments in interface files are merged with the comments in implementation files keep code Always keep the source code for values methods and instance variables when available The source code is always kept when a m1 file is given but is by default discarded when a mli is given This option allows to always keep the source code load file Load information from file which has been produced by ocamldoc dump Several load options can be given m flags ae merge options between interfaces and implementations see section for details flags can be one or several of the following characters d merge description a merge author v merge version l1 merge Qsee s merge Qsince o merge Qdeprecated p merge param merge raise merge return merge everything no custom tags Do not allow custom tags see section 15 2 5 no stop Keep elements placed after the special comment see section 15 2 o file Output the generated documentation to file instead of ocamldoc out This option is mean ingful only in conjunction with the latex texi or dot options pp command Pipe sources through preprocessor command sort Sort the list of top le
558. v in case of an error val usage key spec doc list gt usage_msg gt unit Arg usage speclist usage_msg prints an error message including the list of valid options This is the same message that Arg parse prints in case of error speclist and usage_msg are the same as for Arg parse val align key spec doc list gt key spec doc list Align the documentation strings by inserting spaces at the first space according to the length of the keyword Use a space as the first character in a doc string if you want to align the whole string The doc strings corresponding to Symbol arguments are not aligned val current int Pervasives ref Position in Sys argv 20 34 of the argument being processed You can change this value e g to force Arg parse to skip some arguments Arg parse 20 uses the initial value of Arg current as the index of argument 0 the program name and starts parsing arguments at the next element 20 2 Module Array Array operations val length a array gt int Return the length number of elements of the given array val get a array gt int gt a 290 Array get a n returns the element number n of array a The first element has number 0 The last element has number Array length a 1 You can also write a n instead of Array get a n Raise Invalid_argument index out of bounds if n is outside the range 0 to Array length a 1 val set a array gt int gt
559. val float float gt float Random float bound returns a random floating point number between 0 inclusive and bound exclusive If bound is negative the result is negative or zero If bound is 0 the result is 0 val bool unit gt bool Random bool returns true or false with probability 0 5 each Chapter 20 The standard library 347 Advanced functions The functions from module State manipulate the current state of the random generator explicitely This allows using one or several deterministic PRNGs even in a multi threaded program without interference from other parts of the program module State sig type t val val val val val val val val val val end The type of PRNG states make int array gt t Create a new state and initialize it with the given seed make_self_init unit gt t Create a new state and initialize it with a system dependent low entropy seed copy t gt t Return a copy of the given state bits t gt int int t gt int gt int int32 t gt Int32 t gt Int32 t nativeint t gt Nativeint t gt Nativeint t int64 t gt Int64 t gt Int64 t float t gt float gt float bool t gt bool These functions are the same as the basic functions except that they use and update the given PRNG state instead of the default one val get_state unit gt State t Return the current state of the generator used by the basic
560. ve data in the major heap including the header words live_blocks int Number of live blocks in the major heap free_words int Number of words in the free list free_blocks int Number of blocks in the free list largest_free int Size in words of the largest block in the free list fragments int Number of wasted words due to fragmentation These are 1 words free blocks placed between two live blocks They are not available for allocation compactions int Number of heap compactions since the program was started top_heap_words int Maximum size reached by the major heap in words The memory management counters are returned in a stat record The total amount of memory allocated by the program since it was started is in words minor_words major_words promoted_words Multiply by the word size 4 on a 32 bit machine 8 on a 64 bit machine to get the number of bytes type control mutable minor_heap_size int The size in words of the minor heap Changing this parameter will trigger a minor collection Default 32k mutable major_heap_increment int Chapter 20 The standard library 313 The minimum number of words to add to the major heap when increasing it Default 62k mutable space_overhead int The major GC speed is computed from this parameter This is the memory that will be wasted because the GC does not immediatly collect unreachable blocks It is express
561. vel modules before generating the documentation stars Remove blank characters until the first asterisk in each line of comments 198 t title Use title as the title for the generated documentation intro file Use content of file as ocamldoc text to use as introduction HTML ATFXand TeXinfo only For HTML the file is used to create the whole index html file v Verbose mode Display progress information warn error Treat warnings as errors Type checking options OCamldoc calls the Objective Caml type checker to obtain type informations The following options impact the type checking phase They have the same meaning as for the ocamlc and ocamlopt commands I directory Add directory to the list of directories search for compiled interface files cmi files nolabels Ignore non optional labels in types rectypes Allow arbitrary recursive types See the rectypes option to ocamlc Options for generating HTML pages The following options apply in conjunction with the htm1 option all params Display the complete list of parameters for functions and methods css style filename Use filename as the Cascading Style Sheet file colorize code Colorize the OCaml code enclosed in and using colors to emphasize keywords etc If the code fragments are not syntactically correct no color is added index only Generate only index files Options for generating ATEX files The following opt
562. ven input does not match the format Raise Failure if a conversion to a number is not possible Raise End_of_file if the end of input is encountered while scanning and the input matches the given format so far The format is a character string which contains three types of objects e plain characters which are simply matched with the characters of the input e conversion specifications each of which causes reading and conversion of one argument for f e scanning indications to specify boundaries of tokens Among plain characters the space character ASCII code 32 has a special meaning it matches whitespace that is any number of tab space newline and carriage return characters Hence a space in the format matches any amount of whitespace in the input Conversion specifications consist in the character followed by an optional flag an optional field width and followed by one or two conversion characters The conversion characters and their meanings are e d reads an optionally signed decimal integer e i reads an optionally signed integer usual input formats for hexadecimal Ox d and OX d octal Oo d and binary Ob d notations are understood e u reads an unsigned decimal integer 390 x or X reads an unsigned hexadecimal integer o reads an unsigned octal integer s reads a string argument by default strings end with a space S reads a delimited string argument delimiters and special escap
563. vings in effect The type representing wallclock time and calendar date time unit gt float Return the current time since 00 00 00 GMT Jan 1 1970 in seconds gettimeofday unit gt float Same as Unix time 21 1 but with resolution better than 1 second gmtime float gt tm Convert a time in seconds as returned by Unix time into a date and a time Assumes UTC Coordinated Universal Time also known as GMT localtime float gt tm Convert a time in seconds as returned by Unix time into a date and a time Assumes the local time zone mktime tm gt float tm Convert a date and time specified by the tm argument into a time in seconds as returned by Unix time 21 The tm_isdst tm_wday and tm_yday fields of tm are ignored Also return a normalized copy of the given tm record with the tm_wday tm_yday and tm_isdst fields recomputed from the other fields and the other fields normalized so that e g 40 October is changed into 9 November The tm argument is interpreted in the local time zone alarm int gt int Schedule a SIGALRM signal after the given number of seconds Chapter 21 The unix library Unix system calls 391 val sleep int gt unit Stop execution for the given number of seconds val times unit gt process_times Return the execution times of the process val utimes string gt float gt float gt unit Set the last access time second arg and last modifi
564. w option an uppercase character turns the corresponding warning into an error a lowercase character leaves it as a warning The default setting is warn error a all warnings are not treated as errors where Print the location of the standard library then exit 8 3 Modules and the file system This short section is intended to clarify the relationship between the names of the modules corre sponding to compilation units and the names of the files that contain their compiled interface and compiled implementation The compiler always derives the module name by taking the capitalized base name of the source file ml or mli file That is it strips the leading directory name if any as well as the ml or mli suffix then it set the first letter to uppercase in order to comply with the requirement that module names must be capitalized For instance compiling the file mylib misc ml provides an implementation for the module named Misc Other compilation units may refer to components defined in mylib misc ml under the names Misc name they can also do open Misc then use unqualified names name The cmi and cmo files produced by the compiler have the same base name as the source file Hence the compiled files always have their base name equal modulo capitalization of the first letter to the name of the module they describe for cmi files or implement for cmo files When the compiler encounters a reference to a free module identifier M
565. wing the last character of substring that was matched by the nth group of the regular expression Raises e Not_found if the nth group of the regular expression was not matched e Invalid_argument if there are fewer than n groups in the regular expression Replacement val global_replace regexp gt string gt string gt string global_replace regexp templ s returns a string identical to s except that all substrings of s that match regexp have been replaced by templ The replacement template templ can contain 1 2 etc these sequences will be replaced by the text matched by the corresponding group in the regular expression 0 stands for the text matched by the whole regular expression val replace_first regexp gt string gt string gt string Same as Str global_replace 23 1 except that only the first substring matching the regular expression is replaced val global_substitute regexp gt string gt string gt string gt string global_substitute regexp subst s returns a string identical to s except that all substrings of s that match regexp have been replaced by the result of function subst The function subst is called once for each matching substring and receives s the whole text as argument val substitute_first regexp gt string gt string gt string gt string Same as Str global_substitute 23 1 except that only the first substring matching the regular expression is replaced val r
566. xpr parser lt Int n gt gt n lt Kwd n parse_expr Kwd gt gt n lt n1 parse_expr n2 parse_remainder n1 gt gt n2 and parse_remainder n1 parser lt Kwd n2 parse_expr gt gt ni n2 type token Kwd of string Ident of string Int of int Float of float String of string Char of char The type of tokens The lexical classes are Int and Float for integer and floating point numbers String for string literals enclosed in double quotes Char for character literals enclosed in single quotes Ident for identifiers either sequences of letters digits underscores and quotes or sequences of operator characters such as etc and Kwd for keywords either identifiers or single special characters such as etc val make_lexer string list gt char Stream t gt token Stream t Chapter 20 The standard library 317 Construct the lexer function The first argument is the list of keywords An identifier s is returned as Kwd s if s belongs to this list and as Ident s otherwise A special character s is returned as Kwd s if s belongs to this list and cause a lexical error exception Parse_error otherwise Blanks and newlines are skipped Comments delimited by and are skipped as well and can be nested 20 12 Module Hashtbl Hash tables and hash functions Hash tables are hashed association tables with in place modification Generic inter
567. xpression typexpr gt typexpry denotes the type of functions mapping arguments of type typexpr to results of type typexprs label name typexpr gt typexpr denotes the same function type but the argument is labeled label optlabel typexpr gt typexprz denotes the type of functions mapping an optional labeled argument of type typexpr to results of type typexpry That is the physical type of the function will be typexpr option gt typexpro Tuple types The type expression typexpr typexpr denotes the type of tuples whose elements belong to types typexpr typexpr respectively Constructed types Type constructors with no parameter as in typeconstr are type expressions The type expression typexpr typeconstr where typeconstr is a type constructor with one pa rameter denotes the application of the unary type constructor typeconstr to the type typexpr The type expression typexpr typexpr typeconstr where typeconstr is a type construc tor with n parameters denotes the application of the n ary type constructor typeconstr to the types typexpr through typexpr Aliased and recursive types The type expression typexpr as ident denotes the same type as typexpr and also binds the type variable ident to type typexpr both in typexpr and in the remaining part of the type If the type variable ident actually occurs in typexpr a recursive type is created Recursive types for which there exists a recursive
568. xt of the interactive system However modules are most useful for large batch compiled programs For these programs it is a practi 32 cal necessity to split the source into several files called compilation units that can be compiled separately thus minimizing recompilation after changes In Objective Caml compilation units are special cases of structures and signatures and the relationship between the units can be explained easily in terms of the module system A compilation unit A comprises two files e the implementation file A m1 which contains a sequence of definitions analogous to the inside of a struct end construct e the interface file A mli which contains a sequence of specifications analogous to the inside of a sig end construct Both files define a structure named A as if the following definition was entered at top level module A sig contents of file A mli end struct contents of file A ml end The files defining the compilation units can be compiled separately using the ocamlc c command the c option means compile only do not try to link this produces compiled interface files with extension cmi and compiled object code files with extension cmo When all units have been compiled their cmo files are linked together using the ocaml command For instance the following commands compile and link a program composed of two compilation units Aux and Main ocamlc c Aux mli produce
569. y info section Specify section of Info directory noheader Suppress header in generated documentation noindex Do not build index for Info files notrailer Suppress trailer in generated documentation 200 Options for generating dot graphs The following options apply in conjunction with the dot option dot colors colors Specify the colors to use in the generated dot code When generating module dependencies ocamldoc uses different colors for modules depending on the directories in which they reside When generating types dependencies ocamldoc uses different colors for types depending on Oe wid the modules in which they are defined colors is a list of color names separated by as in Red Blue Green The available colors are the ones supported by the dot tool dot include all Include all modules in the dot output not only modules given on the command line or loaded with the load option dot reduce Perform a transitive reduction of the dependency graph before outputting the dot code This can be useful if there are a lot of transitive dependencies that clutter the graph dot types Output dot code describing the type dependency graph instead of the module dependency graph Options for generating man files The following options apply in conjunction with the man option man mini Generate man pages only for modules module types clases and class types instead of pages for all elements man
570. y 283 val seek_in Pervasives in_channel gt int64 gt unit val pos_in Pervasives in_channel gt int64 val in_channel_length Pervasives in_channel gt int64 end Operations on large files This sub module provides 64 bit variants of the channel functions that manipulate file positions and file sizes By representing positions and sizes by 64 bit integers type int64 instead of regular integers type int these alternate functions allow operating on files whose sizes are greater than max_int References type a ref mutable contents a The type of references mutable indirection cells containing a value of type a val ref a gt a ref Return a fresh reference containing the given value val a ref gt a I r returns the current contents of reference r Equivalent to fun r gt r contents val a ref gt a gt unit r a stores the value of a in reference r Equivalent to fun r v gt r contents lt v val incr int ref gt unit Increment the integer contained in the given reference Equivalent to fun r gt r succ Ir val decr int ref gt unit Decrement the integer contained in the given reference Equivalent to fun r gt r pred Ir Operations on format strings See modules Printf 20 24 and Scanf 20 27 for more operations on format strings type a b c format a b c c format4 Simplified type for
571. ype definition in the signature specifies an optional type equation typexp and an optional type representation constr decl or label decl The implementation of the type name in a matching structure must be compatible with the type expression specified in the equation if given and have the specified representation if given Conversely users of that signature will be able to rely on the type equation or type representation if given More precisely we have the following four situations Abstract type no equation no representation Names that are defined as abstract types in a signature can be implemented in a matching structure by any kind of type definition provided it has the same number of type param eters The exact implementation of the type will be hidden to the users of the structure In particular if the type is implemented as a variant type or record type the associated constructors and fields will not be accessible to the users if the type is implemented as an abbreviation the type equality between the type name and the right hand side of the abbre viation will be hidden from the users of the structure Users of the structure consider that type as incompatible with any other type a fresh type has been generated Type abbreviation an equation typexp no representation The type name must be implemented by a type compatible with typexp All users of the structure know that the type name is compatible with typexp
572. zation code registers callback functions using Callback register Once the Caml initialization code is complete control returns to the C code that called caml_main e The C code can then invoke Caml functions using the callback mechanism see section 18 7 1 18 7 5 Embedding the Caml code in the C code The bytecode compiler in custom runtime mode ocamlc custom normally appends the bytecode to the executable file containing the custom runtime This has two consequences First the final linking step must be performed by ocamlc Second the Caml runtime library must be able to find the name of the executable file from the command line arguments When using caml_main argv as in section 18 7 4 this means that argv 0 or argv 1 must contain the executable file name An alternative is to embed the bytecode in the C code The output obj option to ocamlc is provided for this purpose It causes the ocamlc compiler to output a C object file o file containing the bytecode for the Caml part of the program as well as a caml_startup function The C object file produced by ocamlc output obj can then be linked with C code using the standard C compiler or stored in a C library The caml_startup function must be called from the main C program in order to initialize the Caml runtime and execute the Caml initialization code Just like caml_main it takes one argv parameter containing the command line parameters Unlike caml_main this argv parameter is u

The Objective Caml system release 3.08

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