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The Caml Light system release 0.74 - The Caml language

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2. addstr String_val s return Val_unit This goes on for pages Actually it would be better to create a library for the stub code with each stub code function in a separate file so that linking would pick only those functions from the curses library that are actually used The file curses c can be compiled with cc c I usr local lib caml light curses c or even simpler camlc c curses c When passed a c file the camlc command simply calls cc on that file with the right I option g Now here is a sample Caml Light 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 camlc c test ml Finally to link everything together camlc custom o test test zo curses o lcurses 110 Part IV The Caml Light library 111 Chapter 13 The core library This chapter describes the functions provided by the Caml Light core library This library is special in two ways e It is automatically linked with the user s object code files by the camlc command chapter 4 Hence the globals defined by these libraries can be used in standalone programs without having to add any zo file on the command line for the linking phase Similarly in interactive use these globals can b
3. Field v n vn If the block has been allocated with alloc_shr filling is performed through the initialize function initialize amp Field v n va 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_long 0 then allocate then modify the fields with the correct value see rule 3 Rule 2 Local variables containing values must be registered with the garbage collector using the Push_roots and Pop_roots macros if they are to survive a call to an allocation function Registration is performed with the Push_roots and Pop_roots macros Push_roots r n declares an array r of n values and registers them with the garbage collector The values contained in r 0 to r n 1 are treated like roots by the garbage collector A root value has the following properties if it points to a heap allocated block this block and its contents will not be reclaimed moreover if this block is relocated by the garbage collector the root value is updated to point to the new location for the block Push_roots r n must occur in a C block exactly between the last local variable declaration and the first statement in the block To un register the roots Pop_
4. Ignore CR on input Map CR to NL on input Recognize XON XOFF characters on input Emit XON XOFF chars to control input flow Enable output processing Output baud rate O means close connection Input baud rate Number of bits per character 5 8 Number of stop bits 1 2 Reception is enabled Enable parity generation and detection Specify odd parity instead of even Hang up on last close Ignore modem status lines Generate signal on INTR QUIT SUSP Enable canonical processing line buffering and editing Disable flush after INTR QUIT SUSP Echo input characters Echo ERASE to erase previous character Echo KILL to erase the current line Echo NL even if c_echo is not set Interrupt character usually ctrl1 C Quit character usually ctrl1 Erase character usually DEL or ctrl H Kill line character usually ctrl1 U End of file character usually ctrl D Alternate end of line char usually none Minimum number of characters to read 190 before the read request is satisfied mutable c_vtime int Maximum read wait in 0O 1s units mutable c_vstart char Start character usually ctrl Q mutable c_vstop char Stop character usually ctrl S value tcgetattr file_descr gt terminal_io Return the status of the terminal referred to by the given file descriptor type setattr_whe
5. 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 Chapter 14 The standard library 159 14 17 stack stacks This module implements stacks LIFOs with in place modification type a t The type of stacks containing elements of type a exception Empty Raised when pop is applied to an empty stack value new unit gt at Return a new stack initially empty value push a gt a t gt unit push x s adds the element x at the top of stack s value pop at gt a pop s removes and returns the topmost element in stack s or raises Empty if the stack is empty value clear a t gt unit Discard all elements from a stack value length a t gt int Return the number of elements in a stack value iter a gt unit gt at 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 14 18 sys system interface This module provides a simple interface to the operating system exception Sys_error of string Raised by some functions in the sys and io modules when the underlying system calls fail The argument to Sys_error is a string describing the error The texts o
6. b find x m returns the current binding of x in m or raises Not_found if no such binding exists value remove a gt a b t gt Ca b t remove x mreturns a map containing the same bindings as m except the current binding for x The previous binding for x is restored if it exists m is returned unchanged if x is not bound in m value iter a gt b gt unit gt Ca b t gt unit iter f m applies f to all bindings in map m discarding the results f receives the key as first argument and the associated value as second argument The order in which the bindings are passed to f is unspecified Only current bindings are presented to f bindings hidden by more recent bindings are not passed to f 14 10 parsing the run time library for parsers generated by camlyacc value symbol_start unit gt int value symbol_end unit gt int symbol_start and symbol_end are to be called in the action part of a grammar rule only They return the position of the string that matches the left hand side of the rule symbol_start returns the position of the first character symbol_end returns the position of the last character plus one The first character in a file is at position 0 154 value rhs_start int gt int value rhs_end int gt int Same as symbol_start and symbol_end above but return the position of the string matching the nth item on the right hand side of the rule where n is the integer par
7. 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 messages with the heap size growing slowly this is 66 Chapter 7 The librarian camllibr Mac This command is a MPW tool not a standalone Macintosh application 7 1 Overview The camllibr program packs in one single file a set of bytecode object files zo files The resulting file is also a bytecode object file and also has the zo extension It can be passed to the link phase of the camlc compiler in replacement of the original set of bytecode object files That is after running camllibr o library zo mod1 zo mod2 zo mod3 zi mod4 zo all calls to the linker with the form camlc library zo are exactly equivalent to camlc modi zo mod2 zo mod3 z1 mod4 zo The typical use of camllibr is to build a library composed of several modules this way users of the library have only one zo file to specify on the command line to camlc instead of a bunch of zo files one per module contained in the library The linking phase of camlc is clever enough to discard the code corresponding to useless phrases in particular definitions for global variables that are never used after their definitions Hence there is no problem with putting many modules even rarely used o
8. value exit int gt a Flush all pending writes on std_out and std_err and 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 This function should be called at the end of all standalone programs that output results on std_out or std_err otherwise the program may appear to produce no output or its output may be truncated Output functions on standard output value print_char char gt unit Print the character on standard output Chapter 13 The core library 123 value print_string string gt unit Print the string on standard output value print_int int gt unit Print the integer in decimal on standard output value print_float float gt unit Print the floating point number in decimal on standard output value print_endline string gt unit Print the string followed by a newline character on standard output value print_newline unit gt unit Print a newline character on standard output and flush standard output This can be used to simulate line buffering of standard output Output functions on standard error value prerr_char char gt unit Print the character on standard error value prerr_string string gt unit Print the string on standard error value prerr_int int gt unit Print the integer in decimal on standard error value prerr_float float gt unit Print
9. Chapter 16 The unix library Unix system calls 173 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 ELOOP Too many levels of symbolic links ENAMETOOLONG File name too long EHOSTDOWN Host is down EHOSTUNREACH No route to host ENOTEMPTY Directory not empty EPROCLIM Too many processes EUSERS Too many users EDQUOT Disc quota exceeded ESTALE Stale NFS file handle EREMOTE Too many levels of remote in path EIDRM Identifier removed EDEADLK Deadlock condition ENOLCK No record locks available ENOSYS Function not implemented EUNKNOWNERR The type of error codes 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 value error_message error gt string Return a string describing the given error code value 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
10. 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 The reader interested in truly formal descriptions of languages from the ML family is referred to The definition of Standard ML and Commentary on Standard ML by Milner Tofte and Harper MIT Press Warning Several implementations of the Caml Light language are available and they evolve at each re lease Consequently this document carefully distinguishes the language and its implementations Implementations can provide extra language constructs moreover all points left unspecified in this reference manual can be interpreted differently by the implementations The purpose of this reference manual is to specify those features that all implementations must provide 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 13
11. 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 top of the screen and angles are measured counterclockwise in degrees Drawing is clipped to the screen Screen pixel at a y x size_x 163 164 Here are the graphics mode specifications supported by open_graph on the various implementations of this library Unix 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 Mae The argument to open_graph is ignored PC The argument to open_graph has the format widthxheight or widthxheight a y where width and height are the initial dimensions of the graphics windows and z and y are the positio
12. a gt a list gt bool memq a 1 is true if and only if a is physically equal see module eq to an element of 1 value except a gt a list gt a list except a 1 returns the list 1 where the first element structurally equal to a has been removed The list 1 is returned unchanged if it does not contain a value exceptq a gt a list gt a list Same as except with physical equality instead of structural equality value subtract a list gt a list gt a list subtract 11 12 returns the list 11 where all elements structurally equal to one of the elements of 12 have been removed value union a list gt a list gt a list union 11 12 appends before list 12 all the elements of list 11 that are not structurally equal to an element of 12 value intersect a list gt a list gt a list intersect 11 12 returns the list of the elements of 11 that are structurally equal to an element of 12 value index a gt a list gt int index a 1 returns the position of the first element of list 1 that is structurally equal to a The head of the list has position 0 Raise Not_found if a is not present in 1 value assoc a gt a b list gt b assoc a 1 returns the value associated with key a in the list of pairs 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
13. expression binds local variables The expressions are evaluated and their values are matched against the left hand sides of the sides as explained in section 2 7 1 If the matching succeeds the bindings of identifiers to values performed during matching are interpreted as bindings to the global value variables whose local name is the identifier and whose module name is the name of the module If the matching fails the exception Match_failure is raised The scope of these bindings is the phrases that follow the value definition in the module implementation Type and exception definitions introduce type constructors variant constructors and record labels as described in sections 2 8 1 and 2 8 2 The scope of these definitions is the phrases that follow the value definition in the module implementation The evaluation of an implementation phrase consisting in a type or exception definition produces no effect at run time Directives modify the behavior of the compiler on the subsequent phrases of the module im plementation as described in section 2 9 The evaluation of an implementation phrase consisting in a directive produces no effect at run time Directives apply only to the module currently being compiled in particular they have no effect on other modules that refer to globals exported by the module being compiled 2 11 Module interfaces interface intfphrase value declaration type definition exception definition directive
14. intf phrase value declaration value ident typexpr and ident typexpr Module interfaces declare the global objects value variables type constructors variant con structors record labels that a module exports that is makes available to other modules Other modules can refer to these globals using qualified identifiers or the open directive as explained in section 2 2 A module interface consists in a sequence of interface phrases terminated by double semicolons An interface phrase is either a value declaration a type definition an exception definition or a directive Value declarations declare global value variables that are exported by the module implementa tion and the types with which they are exported The module implementation must define these variables with types at least as general as the types declared in the interface The scope of the bindings for these global variables extends from the module implementation itself to all modules that refer to those variables Chapter 2 The core Caml Light language 33 Type or exception definitions introduce type constructors variant constructors and record la bels as described in sections 2 8 1 and 2 8 2 Exception definitions and type definitions that are not abstract type declarations also take effect in the module implementation that is the type construc tors variant constructors and record labels they define are considered bound on entrance to the module implementat
15. 1 n Records with up to 214 1 fields 16383 fields must be supported though implementations may support records with more fields 2 3 4 Arrays Arrays are finite variable sized sequences of values of the same type Arrays of length up to 214 1 16383 elements must be supported though implementations may support larger arrays 2 3 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 cconstr the latter case is written ncconstr v where v is said to be the argument of the non constant constructor ncconstr The following constants are treated like built in constant constructors Constant Constructor false the boolean false true the boolean true O the unit value LJ the empty list 2 3 6 Functions Functional values are mappings from values to values Chapter 2 The core Caml Light language 19 2 4 Type expressions typexpr ident typexpr typexpr gt typexpr typexpr typexpr typeconstr typexpr typeconstr typexpr typexpr typeconstr The table below shows the relative precedences and associativity of operators and non closed type constructions The constructions with higher precedences come first Associativi Type constructor application right Type expressions denote types in definitions of data types as well as in type constraints over patterns and expressions Typ
16. 1 where n is the size of the array The exception Invalid_argument is raised if the access is out of bounds The expression expr expr lt expr is equivalent to vect_assign expr expr exprs In the initial environment the identifier vect_assign resolves to a built in function that modifies in place the array denoted by expr replacing element number expr by the value of expr3 The exception Invalid_argument is raised if the access is out of bounds The built in function returns Hence the whole expression expr expr lt expr evaluates to the unit value This behavior of the two constructs expr expr and expr exprs lt expr may change if the meaning of the identifiers vect_item and vect_assign is changed either by redefinition or by modification of the list of opened modules See the discussion below on operators 2 7 4 Operators The operators written infix op in the grammar above can appear in infix position between two expressions The operators written prefix op in the grammar above can appear in prefix position in front of an expression The expression prefix op expr is interpreted as the application ident expr where ident is the identifier associated to the operator prefix op in the table below Similarly the expression expr infix op expr is interpreted as the application ident expr expr where ident is the iden tifier associated to the operator infix op in the table below The identifiers writte
17. at gt at Union intersection and set difference value equal a t gt a t gt bool equal s1 s2 tests whether the sets s1 and s2 are equal that is contain the same elements value compare at gt at gt int Total ordering between sets Can be used as the ordering function for doing sets of sets value elements a t gt a list Return the list of all elements of the given set The elements appear in the list in some non specified order value iter a gt unit gt a t gt unit iter f s applies f in turn to all elements of s and discards the results The elements of s are presented to f in a non specified order value fold a gt b gt b gt at gt b gt b fold f s a computes f xN x2 f x1 a where x1 xN are the elements of s The order in which elements of s are presented to f is not specified value choose at gt a Return one element of the given set or raise Not_found if the set is empty Which element is chosen is not specified but equal elements will be chosen for equal sets 14 16 sort sorting and merging lists value sort 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 value merge a gt a gt bool gt a list gt a list gt
18. expr works also if ident is an identifier bound by pattern matching to the value of a mutable field in a record For instance type bar mutable 1b1l int let x 1b1 1 in begin match x with lbl y gt y lt 2 end x returns the value 1bl 2 3 7 String access Extra syntactic constructs are provided to access and modify characters in strings expr is expr expr expr expr lt expr The expression expr expr is equivalent to the application nth_char expr expr In the initial environment the identifier nth_char resolves to a built in function that returns the character number expr in the string denoted by expr The first element has number 0 the last element 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 exprs is equivalent to set_nth_char expr expr expr3 In the initial environment the identifier set_nth_char resolves to a built in function that modifies in place the string denoted by expr replacing character number expr by the value of expr The exception Invalid_argument is raised if the access is out of bounds The built in function returns O 3 8 Alternate syntax The syntax of some constructs has been slightly relaxed e An optional may terminate a sequence list expression or record expression For instance begin e1 e2 end is syntactically correct an
19. gt Comments are delimited by and as in Caml Light 8 2 1 Header The header section is arbitrary Caml Light text enclosed in curly braces It can be omitted If it is present the enclosed text is copied as is at the beginning of the output file Typically the header section contains the open directives required by the actions and possibly some auxiliary functions used in the actions 8 2 2 Entry points The names of the entry points must be valid Caml Light identifiers 8 2 3 Regular expressions The regular expressions are in the style of lex with a more Caml like syntax 4 4 char A character constant with the same syntax as Caml Light character constants Match the denoted character Match any character eof Match the end of the lexer input string A string constant with the same syntax as Caml Light string constants Match the corre sponding sequence of characters Chapter 8 Lexer and parser generators camllex camlyacc 73 L character set Match any single character belonging to the given character set Valid character sets are single character constants c ranges of characters cy c3 all characters between c and c2 inclusive and the union of two or more character sets denoted by concatenation 4 character set Match any single character not belonging to the given character set regexp Repetition Match the concatenation of zero or more strings
20. in_channel gt unit Close the given channel Anything can happen if any of the functions above is called on a closed channel 13 12 list operations on lists value list_length a list gt int Return the length number of elements of the given list value prefix a list gt a list gt a list List concatenation 128 value hd a list gt a Return the first element of the given list Raise Failure hd if the list is empty value tl a list gt a list Return the given list without its first element Raise Failure t1 if the list is empty value rev a list gt a list List reversal value map Ca gt b gt a list gt b list map f al an applies function f to at an and builds the list f a1 f an with the results returned by f value do_list a gt unit gt a list gt unit do_list f a1 an applies function f in turn to ai an discarding all the results It is equivalent to begin f a1 f a2 f an end value it_list a gt b gt a gt a gt b list gt a it_list f a bi bn isf f a bi b2 bn value list_it a gt b gt b gt a list gt b gt b list_it f ai an bisf al f a2 f an b value map2 a gt b gt c gt a list gt b list gt c list map2 f al an b1 bn is f a1
21. lt stream component stream component gt function stream matching match expr with stream matching stream component expr expr stream matching stream pattern gt expr stream pattern gt expr stream pattern lt gt lt stream comp pat stream comp pat gt stream comp pat gt pattern expr pattern ident Stream expressions are bracketed by lt and gt They represent the concatenation of their components The component expr represents the one element stream whose element is the value 35 36 of expr The component expr represents a sub stream For instance if both s and t are streams of integers then lt 1 s t 2 gt is a stream of integers containing the element 1 then the elements of s then those of t and finally 2 The empty stream is denoted by lt gt Unlike any other kind of expressions in the language stream expressions are submitted to lazy evaluation the components are not evaluated when the stream is built but only when they are accessed during stream matching The components are evaluated once the first time they are accessed the following accesses reuse the value computed the first time Stream patterns also bracketed by lt and gt describe initial segments of streams In particular the stream pattern lt gt matches all streams Stream pattern components are matched against the corresponding elements of a stream The component pattern matches
22. parse e Nt Token lexbuf skip blanks n EOL 60 9 INTCint_of_string get_lexeme lexbuf 6 PLUS MINUS x TIMES DIV ICE LPAREN 9 RPAREN eof raise Eof Here is the main program that combines the parser with the lexer File calc ml try let lexbuf lexing__create_lexer_channel std_in in while true do 78 let result parser__Main lexer__Token lexbuf in print_int result print_newline flush std_out done with Eof gt O To compile everything execute camllex lexer mll generates lexer ml camlyacc parser mly generates parser ml and parser mli camlc c parser mli camlc c lexer ml camlc c parser ml camlc c calc ml camlc o calc lexer zo parser zo calc zo Chapter 9 The debugger camldebug This chapter describes the Caml Light source level replay debugger camldebug Unix The debugger resides in the directory contrib debugger in the distribution It requires a Unix system that provides BSD sockets Mac The debugger is not available PC The debugger is not available 9 1 Compiling for debugging Before the debugger can be used the program must be compiled and linked with the g option all zo files that are part of the program should have been created with camlc g and they must be linked together with camlc g Compiling with g entails no penalty on the running time of programs zo files and byt
23. 0 or 1 according to the sign of the argument value prefix num gt num gt bool value prefix lt num gt num gt bool value prefix gt num gt num gt bool value prefix lt num gt num gt bool value prefix gt num gt num gt bool value prefix lt gt num gt num gt bool value eq_num num gt num gt bool value lt_num num gt num gt bool value le_num num gt num gt bool value gt_num num gt num gt bool value ge_num num gt num gt bool Usual comparisons between numbers value 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 value max_num num gt num gt num value min_num num gt num gt num Return the greater resp the smaller of the two arguments value abs_num num gt num Absolute value value succ_num num gt num succ nis ntt value pred_num num gt num pred nis n 1 value incr_num num ref gt unit incr ris r r 1 where r is a reference to a number value decr_num num ref gt unit decr ris r r 1 where r is a reference to a number 194 Coercions with strings value string_of_num num gt string Convert a number to a string using fractional notation value approx_num_fix int gt num gt string value approx_num_exp int gt num gt string Approximate a number by a decimal The first argument is th
24. 15 1 graphics machine independent graphics primitives 16 The unix library Unix system calls 16 1 unix interface to the Unix system aaaea aaa ee ee 17 The num library arbitrary precision rational arithmetic 17 1 17 2 num operations on numbers s a o ee arith_status flags that control rational arithmetic 18 The str library regular expressions and string processing 18 1 str regular expressions and high level string processing V Appendix 19 Further reading 19 1 19 2 19 3 19 4 Programming in ML sasea e Descriptions of ML dialects a oaa ee Implementing functional programming languages oaoa oaa Applications of ML 2 ee Index to the library Index of keywords 163 164 171 171 191 191 194 197 197 201 203 203 204 205 206 207 216 Foreword This manual documents the release 0 74 of the Caml Light system It is organized as follows e Part I Getting started explains how to install Caml Light on your machine e Part I The Caml Light language reference manual is the reference description of the Caml Light language e Part II The Caml Light commands documents the Caml Light compiler toplevel system and programming utilities e Part IV The Caml Light library describes the modules provided in the standard library e Part V Appendix contains a short bibliography an index
25. For instance Atom 0 represents false and Atom 1 represents true As a convenience mlvalues h defines the macros Val_unit Val_false and Val_true Chapter 12 Interfacing C with Caml Light 105 alloc 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 e alloc_tuple n returns a fresh small block of size n lt Max_young_wosize words with tag 0 The fields of this block must be filled with legal values before the next allocation or modification e 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 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 e alloc_string n returns a string value of length n characters The string initially contains garbage e copy_string s returns a string value containing a copy of the null terminated C string s a char e copy_double d returns a floating point value ini
26. Raise Invalid_argument char_of_int if the argument is outside the range 0 255 value string_of_char char gt string Return a string representing the given character value char_for_read char gt string Return a string representing the given character with special characters escaped following the lexical conventions of Caml Light 13 4 eq generic comparisons value prefix 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 object Equality between functional values raises Invalid_argument Equality between cyclic data structures may not terminate value prefix lt gt a gt a gt bool Negation of prefix value prefix lt a gt a gt bool value prefix lt a gt a gt bool value prefix gt a gt a gt bool value prefix gt a gt a gt bool Structural ordering functions These functions coincide with the usual orderings over integer string and floating point numbers and extend them to a total ordering over all types The ordering is compatible with prefix As in the case of prefix mutable structures are compared by contents Comparison between functional values raises Invalid_argument Comparison between cyclic structures may not terminate value
27. This module implements the set data structure given a total ordering function 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 type a t The type of sets containing elements of type a value empty a gt a gt int gt at The empty set The argument is 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 Examples a suitable ordering function for type int is prefix You can also use the generic structural comparison function eq__compare value is_empty a t gt bool Test whether a set is empty or not value mem a gt a t gt bool mem x s tests whether x belongs to the set s 158 value add a gt at gt at add x s returns a set containing all elements of s plus x If x was already in s s is returned unchanged value remove a gt at gt at remove x s returns a set containing all elements of s except x If x was not in s s is returned unchanged value union a t gt at gt at value inter at gt at gt at value diff at gt
28. ee 13 15 stream operations on streams oaoa ee 13 16 string string operations a o sooo eee 13 17 vect operations on vectors 2 2 a 14 The standard library 14 1 arg parsing of command line arguments 0 0 000 14 2 baltree basic balanced binary trees 2 a 14 3 filename operations on filenames 2 2 2 0 00000 ee eee eee 91 91 92 92 92 95 95 95 96 97 99 99 101 102 103 105 107 111 113 113 114 115 115 116 117 117 119 119 120 122 127 130 130 131 132 134 14 4 14 5 14 6 14 7 14 8 14 9 14 10 14 11 14 12 14 13 14 14 14 15 14 16 14 17 14 18 format pretty printing 2 ee ee gc memory management control and statistics 000 genlex a generic lexical analyzer 6 e hashtbl hash tables and hash functions 2 000 lexing the run time library for lexers generated by camllex map association tables over ordered types 0 0 0 00002 eee eee parsing the run time library for parsers generated by camlyacc printexc a catch all exception handler 2 2 2 0 0 02 0004 printf formatting printing functions 0 0020004 queue queues aoaaa ee random pseudo random number generator 0 0000000008 set sets over ordered types 2 a sort sorting and merging lists 2 2 2 0 0 0 a stack stacks 2 a sys system interface ee 15 The graphics library
29. float Subtraction value prefix float gt float gt float value prefix float gt float gt float value mult_float float gt float gt float Product value prefix float gt float gt float value prefix float gt float gt float value div_float float gt float gt float Division 118 value prefix float gt float gt float value prefix float gt float gt float value power float gt float gt float Exponentiation value eq_float float gt float gt bool value prefix float gt float gt bool Floating point equality Equivalent to generic equality just faster value neq_float float gt float gt bool value prefix lt gt float gt float gt bool Negation of eq_float value prefix lt float gt float gt bool value 1lt_float float gt float gt bool value prefix gt float gt float gt bool value gt_float float gt float gt bool value prefix lt float gt float gt bool value le_float float gt float gt bool value prefix gt float gt float gt bool value ge_float float gt float gt bool Usual comparisons between floating point numbers value acos float gt float value asin float gt float value atan float gt float value atan2 float gt float gt float value cos float gt float value cosh float gt float value exp float gt flo
30. for the Caml language An extremely crude indentation facility is provided as well as a slightly enhanced next error command to display the location of a compilation error The following key bindings are performed TAB function caml indent command At the beginning of a line indent that line like the line above Successive TABs increase the indentation level by 2 spaces by default can be set with the caml mode indentation variable M TAB function caml unindent command Decrease the indentation level of the current phrase 95 96 C x function caml next error Display the next compilation error just as next error does In addition it puts the point and the mark around the exact location of the error the subexpression that caused the error Under Emacs 19 that subexpression is also highlighted M C h function caml mark phrase Mark the Caml phrase that contains the point the point is put at the beginning of the phrase and the mark at the end Phrases are delimited by the final double semicolon This function does not properly ignore inside string literals or comments C x SPC When the Caml debugger is running as an inferior process section 11 4 below set a break point at the current position of the point M C x or C c C e function caml eval phrase When a Caml toplevel is running as an inferior process section 11 3 below send it the the Caml phrase that contains the point The phrase will then be evalu
31. from the Files menu or use the quit function described below At any point the parsing compilation or evaluation of the current phrase can be interrupted by pressing command period or by selecting the item Interrupt Caml Light in the Caml Light menu This goes back to the prompt The toplevel system is presented as a Windows application named Camlwin exe It should be launched from the Windows file manager or program manager The Terminal windows is split in two panes Phrases are entered and edited in the bottom pane The top pane displays a copy of the input phrases as they are processed by the Caml Light toplevel interspersed with the toplevel responses The Return key sends the contents of the bottom pane to the Caml Light toplevel The Enter key inserts a newline without sending the contents of the Input window This can be configured with the Preferences menu item The contents of the input window can be edited at all times with the standard Windows interface An history of previously entered phrases is maintained and displayed in a separate window To quit the Camlwin application either select Quit from the File menu or use the quit function described below At any point the parsing compilation or evaluation of the current phrase can be interrupted by selecting the Interrupt Caml Light menu item This goes back to the prompt A text only version of the
32. 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 Locking type lock_command F_ULOCK F_LOCK F_TLOCK F_TEST Commands for lockf value lockf Unlock Lock a Lock a Test a a region region and block if already locked region or fail if already locked region for other process locks 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 lseek 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 Signals type signal SIGHUP SIGINT SIGQUIT SIGILL SIGTRAP SIGABRT SIGEMT SIGFPE SIGKILL SIGBUS SIGSEGV SIGSYS SIGPIPE hangup interrupt quit illegal instruction not reset when caught trace trap not reset when caught used by abort EMT instruction floating point exception kill cannot be caught or ignored bus error segmentation violation bad argument to system call write on a pipe with no one to read it 182 SIGALRM alarm clo
33. parenthesized patterns 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 pattern A value matches pattern pattern either ifit matches pattern or if it matches patterny The two sub patterns pattern and pattern must contain no identifiers Hence no bindings are returned by matching against an or pattern Constant patterns A pattern consisting in a constant matches the values that are equal to this constant Variant patterns The pattern ncconstr pattern matches all variants whose constructor is equal to ncconstr and whose argument matches pattern The pattern pattern pattern matches non empty lists whose heads match pattern and whose tails match patterns This pattern behaves like prefix pattern pattern The pattern pattern pattern matches lists of length n whose elements match pattern pattern respectively This pattern behaves like pattern pattern O 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 for i 1 n Record patterns The pattern label pattern label pattern matches records that define at least the labels
34. 6 The runtime system camlrun 65 Truncated bytecode file The file that camlrun 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 at some point and this exception is never caught This causes immediate termination of the program If you wish to know which exception thus escapes use the printexc__f function from the standard library and don t forget to link your program with the g option Out of memory The program being executed requires more memory than available Either the program builds too 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 This happens quite frequently on small microcomputers but is unlikely on Unix machines In other cases the out of memory message reveals an error in your program non terminating recursive 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 camlrun If it displays lots of Growing stack messages this is probably a looping recursive function If it displays lots of Growing heap
35. ML e Xavier Leroy and Pierre Weis Manuel de r f rence du langage Caml InterEditions 1993 The French edition of the present reference manual and user s manual e Robert Harper Introduction to Standard ML Technical report ECS LFCS 86 14 University of Edinburgh 1986 An overview of Standard ML including the module system Terse but still readable e Robin Milner Mads Tofte and Robert Harper The definition of Standard ML The MIT press 1990 A complete formal definition of Standard ML in the framework of structured operational se mantics This book is probably the most mathematically precise definition of a programming language ever written It is heavy on formalism and extremely terse so even readers who are thoroughly familiar with ML will have major difficulties with it e Robin Milner and Mads Tofte Commentary on Standard ML The MIT Press 1991 A commentary on the book above that attempts to explain the most delicate parts and motivate the design choices Easier to read than the Definition but still rather involving e Guy Cousineau and G rard Huet The CAME primer Technical report 122 INRIA 1990 A short description of the original Caml system from which Caml Light has evolved Some familiarity with Lisp is assumed e Pierre Weis et al The CAML reference manual version 2 6 1 Technical report 121 INRIA 1990 The manual for the original Caml system from which Caml Light has evolved Chapter 19 Further re
36. and a set of C functions that implement primitive operations such as input output The usage for camlrun is camlrun options bytecode executable arg arg 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 Light program in the string array sys__command_line 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 4 in most cases the bytecode executable files produced by the camlc command are self executable and manage to launch the camlrun command on themselves auto matically That is assuming caml out is a bytecode executable file caml out arg arg works exactly as camlrun caml out arg arg Notice that it is not possible to pass options to camlrun when invoking caml out directly 63 64 6 2 Options The following command line option is recognized by camlrun V Print out the camlrun version number Exit immediately without executing any byte code file The following environment variable are also consulted CAMLRUNPARAM Set the garbage collection parameters This variable must be a sequence of parameter spec ifications A parameter specification is an option letter followed by an sign and a decimal number There are four options corr
37. argument with the value of the second argument prefix Structural equality test prefix Structural inequality test prefix Physical equality test prefix Physical inequality test prefix Test less than on integers prefix Test less than or equal on integers prefix Test greater than on integers prefix Test greater than or equal on integers prefix lt Test less than on floating point numbers prefix lt Test less than or equal on floating point numbers prefix gt Test greater than on floating point numbers prefix gt Test greater than or equal on floating point numbers The behavior of the x mod or operators is unspecified if the result falls outside of the range of representable integers or floating point numbers respectively See chapter 13 for a more precise description of the behavior of the operators above 2 8 Global definitions This section describes the constructs that bind global identifiers value variables value constructors type constructors record labels 30 2 8 1 Type definitions type definition type typedef and typedef typedef type params ident constr decl constr decl type params ident label decl label decl type params ident typexpr type params ident type params nothing gt ident ident ident ident ident of typexpr constr decl label decl ident
38. by the debugger 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 breakpoint 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 9 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 automatic
39. compare a gt a gt int compare x y returns O if x y a negative integer if x lt y and a positive integer if x gt y The same restrictions as for apply compare can be used as the comparison function required by the set and map modules 116 value min a gt a gt a Return the smaller of the two arguments value max a gt a gt a Return the greater of the two arguments value prefix a gt a gt bool e1 e2 tests for physical equality of e1 and e2 On integers and characters it is the same as 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 prefix is implementation dependent except that e1 e2 implies e1 e2 value prefix a gt a gt bool Negation of prefix 13 5 exc exceptions value raise exn gt a Raise the given exception value A few general purpose predefined exceptions exception Out_of_memory Raised by the garbage collector when there is insufficient memory to complete the computation exception Invalid_argument of string Raised by library functions to signal that the given arguments do not make sense exception Failure of string Raised by library functions to signal that they are undefined on the given arguments exception Not_found Raised by search functions when the desired object could not be found excep
40. empty environment This option is not of general use The default compilation mode is 0 cautious See chapter 13 for a complete listing of the modules in the cautious and fast sets Unix The following environment variables are also consulted LANG When set control which language is used to print the compiler messages see the lang command line option 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 5 2 Toplevel control functions The standard library module toplevel opened by default when the toplevel system is launched provides a number of functions that control the toplevel behavior load files in memory and trace program execution 56 value quit unit gt unit Exit the toplevel loop and terminate the camllight command value include string gt unit Read compile and execute source phrases from the given file The ml extension is automatically added to the file name if not present This is textual inclusion phrases are processed just as if they were typed on standard input In particular global identifiers defined by these phrases are entered in the module named top not in a new module value load string gt unit Load in memory the source code for a module implementation Read compile and execute source phrases from the given file The ml extens
41. gt unit Unit of unit gt unit Float of float gt unit The concrete type describing the behavior associated with a keyword value parse string spec list gt string gt unit gt unit parse speclist anonfun parses the command line calling the functions in speclist whenever appropriate and anonfun on anonymous arguments The functions are called in the same order as they appear on the command line The strings in the string spec list are keywords and must start with a else they are ignored For the user to be able to specify anonymous arguments starting with a include for example String anonfun in speclist exception Bad of string Functions in speclist or anonfun can raise Bad with an error message to reject invalid arguments 14 2 baltree basic balanced binary trees This module implements balanced ordered binary trees All operations over binary trees are applicative no side effects The set and map modules are based on this module This modules gives a more direct access to the internals of the binary tree implementation than the set and map abstractions but is more delicate to use and not as safe For advanced users only type a t Empty Node of at a a t int The type of trees containing elements of type a Empty is the empty tree containing no elements type a contents Nothing Something of a Used with the functions modify and split to represent
42. is printed in the box d is added to the current indentation value 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 value 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 144 Tabulations value open_tbox unit gt unit Open a tabulation box value close_tbox unit gt unit Close the most recently opened tabulation box value 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 value set_tab unit gt unit Set a tabulation mark at the current insertion point value print_tab un
43. is the same function as string_before value last_chars string gt int gt string last_chars s n returns the last n characters of s Formatting value format a unit string printf__format gt a Same as printf__sprintf Part V Appendix 201 Chapter 19 Further reading For the interested reader we list below some references to books and reports related sometimes loosely to Caml Light 19 1 Programming in ML The books below are programming courses taught in ML Their main goal is to teach programming not to describe ML in full details though most contain fairly good introductions to the ML language Some of those books use the Standard ML dialect instead of the Caml dialect so you will have to keep in mind the differences in syntax and in semantics e Pierre Weis and Xavier Leroy Le langage Caml InterEditions 1993 The natural companion to this manual provided you read French This book is a step by step introduction to programming in Caml and presents many realistic examples of Caml programs e Guy Cousineau and Michel Mauny Approche fonctionnelle de la programmation Ediscience 1995 Another Caml programming course written in French with many original examples e Lawrence C Paulson ML for the working programmer Cambridge University Press 1991 A good introduction to programming in Standard ML Develops a theorem prover as a com plete example Contains a presentation of the m
44. label through Jabel and such that the value associated to label match the pattern pattern for 1 n The record value can define more labels than label label the values associated to these extra labels are not taken into account for matching 22 2 7 Expressions expr simple matching multiple matching pattern list let binding prefix op infix op ident variable constant expr begin expr end expr typexpr expr expr expr neconstr expr expr expr expr expr I expr expr I label expr label expr expr expr prefix op expr expr infix op expr expr label expr label lt expr expr expr expr expr lt expr expr amp expr expr or 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 simple matching fun multiple matching function simple matching try expr with simple matching let rec let binding and let binding in expr pattern gt expr pattern gt expr pattern list gt expr pattern list gt expr pattern pattern pattern expr variable pattern list expr mod ae gt t c lt gt lt lt gt gt lt lt gt gt The table below shows the relative precedences and associativity of operators and non closed constructions The constructions with higher prece
45. 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 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 flush the pretty printer as with print_newline a plain character Chapter 14 The standard library 147 value printf a formatter unit format gt a Same as fprintf but output on std_formatter value eprintf a formatter unit format gt a Same as fprintf but output on err_formatter 14 5 gc memory management control and statistics type stat minor_words int promoted_words int major_words int minor_collections int major_collections int heap_words int heap_chunks int live_words int live_blocks int free_words int free_blocks int largest_words int fragments int The memory management counters are returned in a stat record All the numbers are computed since the start of the program The fields of this record are minor_words Number of words allocated in the minor heap promoted_words Number of words allocated in the minor heap that survived a minor collection and were moved to the major heap major_words Number of words
46. not automatically opened at start up Hence the phrase printf__printf 4s s hello world is correctly executed while printf 4s 4s hello world causes the error Variable printf is unbound since none of the currently opened mod ules define a global with local name printf However open printf printf 4s 4s hello world executes correctly 3 Assume the file foo ml resides in the current directory and contains the single phrase let x 1 Chapter 5 The toplevel system camllight 59 When the toplevel starts references to x will cause the error Variable x is unbound References to foo__x will cause the error Cannot find file foo zi since the typechecker is attempting to load the compiled interface for module foo in order to find the type of x To load in memory the module foo just do load foo Then references to foo__x typecheck and evaluate correctly Since load does not open the module it loads references to x will still fail with the error Variable x is unbound You will have to do open foo explicitly for x to complete automatically into foo__x 4 Finally assume the file foo ml above has been previously compiled with the camlc c com mand The current directory therefore contains a compiled interface foo zi claiming that foo__x is a global variable with type int and a compiled bytecode file foo zo defining foo__x to have the value 1 When the to
47. not available PC This command is not available 10 1 Compiling for profiling Before profiling an execution the program must be compiled in profiling mode using the p option to the batch compiler camlc see chapter 4 When compiling modules separately the p option must be given both when compiling the modules production of zo files and when linking them together The amount of profiling information can be controlled by adding one or several letters after the p option 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 the 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 For instance compiling with pfilm profiles function calls if then else loops and pattern matching The p option without additional letters defaults to pfm meaning that only function calls and pattern matching are profiled 91 92 10 2 Profiling an execution Running a bytecode executable file that has been compiled and linked with p records the execution counts for the specified parts of the program and saves them in a file called camlpro dump in the current director
48. of introduction in the table value remove a b t gt a gt unit remove tbl x removes the current binding of x in tbl restoring the previous binding if it exists It does nothing if x is not bound in tbl Chapter 14 The standard library 151 value do_table a gt b gt unit gt a b t gt unit do_table f tbl applies f to all bindings in table tbl discarding all the results 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 unpredictable except that successive bindings for the same key are presented in reverse chronological order most recent first value do_table_rev a gt b gt unit gt a b t gt unit Same as do_table except that successive bindings for the same key are presented in chronological order oldest first The polymorphic hash primitive value hash a gt int hash x associates a positive integer to any value of any type It is guaranteed that ifx y then hash x hash y Moreover hash always terminates even on cyclic structures value hash_param int gt int gt a gt int 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 sto
49. on user interrupt if catch_break is on value catch_break bool gt unit catch_break governs whether user interrupt 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 162 Chapter 15 The graphics library This chapter describes the portable graphics primitives that come standard in the implementation of Caml Light on micro computers Unix On Unix workstations running the X11 windows system an implementation of the graphics Mac PC primitives is available in the directory contrib libgraph in the distribution See the file README in this directory for information on building and using camlgraph a toplevel system that includes the graphics primitives and linking standalone programs with the library Drawing takes place in a separate window that is created when open_graph is called The graphics primitive are available from the standalone application that runs the toplevel system They are not available from programs compiled by camlc and run under the MPW shell Drawing takes place in a separate window that can be made visible with the Show graphics window menu entry The graphics primitive are available from the Windows application that runs the toplevel system They are not available from programs compiled by camlc and run in a DOS command window Drawing takes place in a separate window
50. open_box 141 open_connection 187 open_descriptor_in 126 open_descriptor_out 124 open_graph 164 open_hbox 143 open_hovbox 143 open_hvbox 143 open_in 126 open_in_bin 126 open_in_gen 126 open_out 124 open_out_bin 124 open_out_gen 124 open_process 180 open_process_in 180 open_process_out 180 open_tbox 144 open_vbox 143 opendir 179 or infix 114 out_channel_length 125 out_channel_of_descr 176 Out_of_memory exception 116 output 125 output_binary_int 125 output_byte 125 output_char 125 output_compact_value 125 output_string 125 output_value 125 over_max_boxes 143 pair module 130 parse 138 Parse_error exception 131 154 Parse_failure exception 131 parsing module 153 pause 182 peek 156 pipe 179 plot 166 point_color 166 pop 159 pos_in 127 pos_out 125 power 118 power_num 192 pp_close_box 146 pp_close_tbox 146 pp_force_newline 146 pp_get_ellipsis_text 146 pp_get_formatter_output_functions 146 pp_get_margin 146 pp_get_max_boxes 146 pp_get_max_indent 146 pp_open_box 146 pp_open_hbox 146 pp_open_hovbox 146 pp_open_hvbox 146 pp_open_tbox 146 pp_open_vbox 146 pp_over_max_boxes 146 pp_print_as 146 pp_print_bool 146 pp_print_break 146 pp_print_char 146 pp_print_cut 146 pp_print_float 146 pp_print_flush 146 pp_print_if_newline 146 pp_print_int 146 pp_print_newline 146 pp_print_space 146 pp_print_string 146 pp_print_tab 146
51. pp_print_tbreak 146 pp_set_ellipsis_text 146 pp_set_formatter_out_channel 146 pp_set_formatter_output_functions 146 pp_set_margin 146 Index to the library pp_set_max_boxes 146 pp_set_max_indent 146 pp_set_tab 146 pred 120 pred_num 193 prerr_char 123 prerr_endline 123 prerr_float 123 prerr_int 123 prerr_string 123 print 155 print_as 141 print_bool 141 print_break 142 print_char 122 141 print_cut 142 print_endline 123 print_float 123 141 print_flush 142 print_if_newline 142 print_int 123 141 print_newline 123 142 print_num 194 print_space 142 print_stat 148 print_string 123 141 print_tab 144 print_tbreak 144 printexc module 154 printf 147 155 printf module 154 push 159 queue module 156 quit 56 quo infix 120 quo_num 192 raise 116 random module 157 ratio_of_num 194 read 176 read_float 124 read_int 124 read_key 169 read_line 124 213 readdir 179 readlink 180 really_input 126 recv 187 recvfrom 187 red 165 ref module 130 regexp 197 regexp_case_fold 198 remove 139 150 153 158 161 remove_printer 57 rename 161 177 replace_first 199 replace_string 133 rev 128 rewinddir 179 rgb 165 rhs_end 154 rhs_start 154 rindex_char 133 rindex_char_from 133 rmdir 179 round_num 192 s_irall 160 s_irgrp 160 s_iroth 160 s_irusr 160 s_isgid 160 s_isuid 160 s_iwall 160 s_iwgrp 160 s_iwoth 160 s_iwusr 1
52. report still gives a complete overview of the implementation techniques used in Caml Light e Simon Peyton Jones The implementation of functional programming languages Prentice Hall 1987 French translation Mise en uvre des langages fonctionnels de programmation Masson 1990 An excellent description of the implementation of purely functional languages with lazy se mantics using the technique known as graph reduction The part of the book that deals with the transformation from ML to enriched lambda calculus directly applies to Caml Light You will find a good description of how pattern matching is compiled and how types are inferred The remainder of the book does not apply directly to Caml Light since Caml Light is not purely functional it has side effects has strict semantics and does not use graph reduction at all e Andrew W Appel Compiling with continuations Cambridge University Press 1992 A complete description of an optimizing compiler for Standard ML based on an intermediate representation called continuation passing style Shows how many advanced program opti mizations can be applied to ML Not directly relevant to the Caml Light system since Caml Light does not use continuation passing style at all and makes little attempts at optimizing programs 206 19 4 Applications of ML The following reports show ML at work in various sometimes unexpected areas Emmanuel Chailloux and Guy Cousineau The MLgraph
53. s 1 Raise Invalid_argument nth_char if n is ouside the range 0 to string_length s 1 You can also write s n instead of nth_char s n value set_nth_char string gt int gt char gt unit set_nth_char s n c modifies string s in place replacing the character number n by c Raise Invalid_argument set_nth_char if n is ouside the range 0 to string_length s 1 You can also write s n lt c instead of set_nth_char s n c value prefix string gt string gt string si s2 returns a fresh string containing the concatenation of the strings s1 and s2 value concat string list gt string Return a fresh string containing the concatenation of all the strings in the argument list value sub_string string gt int gt int gt string sub_string 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 sub_string if start and len do not designate a valid substring of s that is if start lt O or len lt 0 or start len gt string_length s value create_string int gt string create_string n returns a fresh string of length n The string initially contains arbitrary characters value make_string int gt char gt string make_string n c returns a fresh string of length n filled with the character c value fill_string string gt int gt int gt char gt unit fill_string s start len c modifies string
54. s in place replacing the characters number start to start len 1 by c Raise Invalid_argument fill_string if start and len do not designate a valid substring of s Chapter 13 The core library 133 value blit_string string gt int gt string gt int gt int gt unit blit_string s1 o1 s2 o2 len copies len characters from string s1 starting at character number o1 to string s2 starting at character number 02 It works correctly even if s1 and s2 are the same string and the source and destination chunks overlap Raise Invalid_argument blit_string if o1 and len do not designate a valid substring of s1 or if o2 and len do not designate a valid substring of s2 value replace_string string gt string gt int gt unit replace_string dest src start copies all characters from the string src into the string dst starting at character number start in dst Raise Invalid_argument replace_string if copying would overflow string dest value eq_string string gt string gt bool value neq_string string gt string gt bool value le_string string gt string gt bool value lt_string string gt string gt bool value ge_string string gt string gt bool value gt_string string gt string gt bool Comparison functions lexicographic ordering between strings value compare_strings string gt string gt int General comparison between strings compare_strings s1 s2 returns 0 if s1 and s2 ar
55. set program file Set the program name to file set arguments arguments Give arguments as command line arguments for the program A shell 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 9 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 Chapter 9 The debugger camldebug 87 set loadingmode runtime The debugger execute the Caml Light runtime camlrun 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 9 8 7 9 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
56. sets p Compile and link in profiling mode See the description of the profiler camlpro in chapter 10 v Print the version number of the compiler W Print extra warning messages for the following events e A open directive is useless no identifier in the opened module is ever referenced e A variable name in a pattern matching is capitalized often corresponds to a misspelled constant constructor Unix The following environment variable is also consulted LANG When set control which language is used to print the compiler messages see the lang command line option PC The following option is also supported response file Process the files whose names are listed in file response file just as if these names appeared on the command line File names in response file are separated by blanks spaces tabs newlines This option allows to overcome silly limitations on the length of the command line The following environment variables are also consulted CAMLLIB Contain the path to the standard library directory Chapter 4 Batch compilation camlc 49 LANG When set control which language is used to print the compiler messages see the lang command line option 4 3 Modules and the file system This short section is intended to clarify the relationship between the names of the modules and the names of the files that contain their compiled interface and compiled implementation The compiler always derives the name
57. substring of buff value 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 value output_binary_int out_channel gt int gt unit Write one integer in binary format on the given output channel The only reliable way to read it back is through the input_binary_int function The format is compatible across all machines for a given version of Caml Light value 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 input_value The format is compatible across all machines for a given version of Caml Light value output_compact_value out_channel gt a gt unit Same as output_value but uses a different format which occupies less space on the file but takes more time to generate and read back value 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 value pos_out out_channel gt int Return the current writing position for the given channel value out_channel_length out_channel gt int Return the total length n
58. the corresponding stream element against the pattern The component expr pattern applies the function denoted by expr to the current stream then matches the result of the function against pattern Finally the component ident simply binds the identifier to the stream being matched The current implementation limits ident to appear last in a stream pattern Stream matching proceeds destructively once a component has been matched it is discarded from the stream by in place modification Stream matching proceeds in two steps first a pattern is selected by matching the stream against the first components of the stream patterns then the following components of the selected pattern are checked against the stream If the following components do not match the exception Parse_error is raised There is no backtracking here stream matching commits to the pattern selected according to the first element If none of the first components of the stream patterns match the exception Parse_failure is raised The Parse_failure exception causes the next alternative to be tried if it occurs during the matching of the first element of a stream before matching has committed to one pattern See Functional programming using Caml Light for a more gentle introductions to streams and for some examples of their use in writing parsers A more formal presentation of streams and a discussion of alternate semantics can be found in Parsers in ML by Michel Mauny and Danie
59. the elements of 1 value map_vect a gt b gt a vect gt b vect map_vect f v applies function f to all the elements of v and builds a vector with the results returned by f I f v 0 v 1 f v vect_length v 1 value map_vect_list a gt b gt a vect gt b list map_vect_list f v applies function f to all the elements of v and builds a list with the results returned by f v 0 f v 1 f v vect_length v 1 value do_vect a gt unit gt a vect gt unit do_vect f v applies function f in turn to all the elements of v discarding all the results f v 0 f v 1 f v vect_length v 1 O 136 Chapter 14 The standard library This chapter describes the functions provided by the Caml Light standard library Just as the modules from the core library the modules from the standard library are automatically linked with the user s object code files by the camlc command Hence the globals defined by these libraries can be used in standalone programs without having to add any zo 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 zo file in memory Unlike the modules from the core library the modules from the standard library are not auto matically opened when a compilation starts or when the toplevel system is launched Hence it is nec
60. the error and exits with code 2 Interface with the parent process value environment unit gt string vect Return the process environment as an array of strings with the format variable value See also sys__getenv 174 Process handling type process_status WEXITED of int WSIGNALED of int bool WSTOPPED of int The termination status of a process WEXITED means that the process terminated normally by exit the argument is the return code WSIGNALED means that the process was killed by a signal the first argument is the signal number the second argument indicates whether a core dump was performed WSTOPPED means that the process was stopped by a signal the argument is the signal number type wait_flag WNOHANG WUNTRACED Flags for waitopt and waitpid WNOHANG means do not block if no child has died yet but immediately return with a pid equal to 0 WUNTRACED means report also the children that receive stop signals value execv string gt string vect gt unit execv prog args execute the program in file prog with the arguments args and the current process environment value execve string gt string vect gt string vect gt unit Same as execv except that the third argument provides the environment to the program executed value execvp string gt string vect gt unit Same as execv except that the program is searched in the path value fork unit gt int Fork a new pr
61. the files directory directorynames Add the given 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 9 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 9 8 5 Module management Like the Caml Light compiler the debugger maintains a list of opened modules in order to resolves variable name ambiguities The opened modules also affect the printing of values whether fully qualified names or short names are used for constructors and record labels When a program is executed the debugger automatically opens the modules of the standard library it uses open modules Open the given modules close modules Close the given modules 88 info modules List the modules used by the program and the open modules 9 8 6 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 int
62. the floating point number in decimal on standard error value prerr_endline string gt unit Print the string followed by a newline character on standard error and flush standard error 124 Input functions on standard input value 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 value 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 value 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 General output functions value 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__Sys_error if the file could not be opened value open_out_bin string gt out_channel Same as open_out but the file is opened in binary mode so that no translation takes place during writes On operating systems that do not distin
63. the presence or the absence of an element in a tree Chapter 14 The standard library 139 value add a gt int gt a gt at gt at add f x t inserts the element x into the tree t f is an ordering function f y must return O if x and y are equal or equivalent a negative integer if x is smaller than y and a positive integer if x is greater than y The tree t is returned unchanged if it already contains an element equivalent to x that is an element y such that f y is 0 The ordering f must be consistent with the orderings used to build t with add remove modify or split operations value contains a gt int gt a t gt bool contains f t checks whether t contains an element satisfying f that is an element x such that f x is O f is an ordering function with the same constraints as for add It can be coarser identify more elements than the orderings used to build t but must be consistent with them value find a gt int gt at gt a Same as contains except that find f t returns the element x such that f x is 0 or raises Not_found if none has been found value remove a gt int gt a t gt at remove f t removes one element x of t such that f x is O f is an ordering function with the same constraints as for add t is returned unchanged if it does not contain any element satisfying f If several elements of t satisfy f only one is removed value modify
64. 0 GMT Jan 1 1970 184 User id group id value getuid unit gt int Return the user id of the user executing the process value geteuid unit gt int Return the effective user id under which the process runs value setuid int gt unit Set the real user id and effective user id for the process value getgid unit gt int Return the group id of the user executing the process value getegid unit gt int Return the effective group id under which the process runs value setgid int gt unit Set the real group id and effective group id for the process value getgroups unit gt int vect Return the list of groups to which the user executing the process belongs type passwd_entry pw_name string pw_passwd string pwiuid 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 vect Structure of entries in the groups database value getlogin unit gt string Return the login name of the user executing the process Chapter 16 The unix library Unix system calls 185 value getpwnam string gt passwd_entry Find an entry in passwd with the given name or raise Not_found value getgrnam string gt group_entry Find an entry in group with the given name or raise Not_found value getpwuid int gt passwd_entry Find an entry in
65. 12 3 Representation of Caml Light data types This section describes how Caml Light data types are encoded in the value type Chapter 12 Interfacing C with Caml Light 103 12 3 1 Atomic types int Unboxed integer values char Unboxed integer values ASCH code float Blocks with tag Double_tag string Blocks with tag String_tag 12 3 2 Product types Tuples and arrays 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 12 3 3 Concrete types Constructed terms are represented by blocks whose tag encode the constructor The constructors for a given concrete type are numbered from 0 to the number of constructors minus one following the order in which they appear in the concrete type declaration Constant constructors are represented by zero sized blocks atoms tagged with 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 const
66. 14 2 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 keywords 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 correctly handled Identifiers ident letter letter 0 9 _ letter A Z a z Identifiers are sequences of letters digits and _ the underscore character starting with a letter Letters contain at least the 52 lowercase and uppercase letters from the ASCII set Implementations can recognize as letters other characters from the extended ASCII set Identifiers cannot contain two adjacent underscore characters __ Implementation may limit the number of characters of an identifier but this limit must be above 256 characters All characters in an identifier are meaningful Integer literals integer literal 0 9 0x 0X 0 9 A F a t oo 100 10 7 Ob OB 0 1 An integer literal is a sequence of one or more digits optionally preceded by a minus sign By default integer literals are in de
67. 159 clear_graph 165 clear_parser 154 close 161 176 close_box 141 close_graph 164 close_in 127 close_out 125 close_process 180 close_process_in 180 close_process_out 180 close_tbox 144 closedir 179 combine 130 command_line 160 compare 115 139 158 compare_num 193 compare_strings 133 compile 56 concat 132 140 200 concat_vect 134 connect 186 contains 139 copy_vect 134 cos 118 cosh 118 create_image 168 create_lexer 152 create_lexer_channel 152 create_lexer_string 152 create_string 132 current_dir_name 140 current_point 166 cyan 165 debug_mode 57 decr 130 decr_num 193 denominator_num 191 descr_of_in_channel 176 descr_of_out_channel 176 diff 158 directory 57 dirname 140 div_float 117 div_int 120 div_num 192 Division_by_zero exception 120 do_list 128 do_list2 128 do_list_combine 130 do_stream 131 do_table 151 do_table_rev 151 do_vect 135 draw_arc 166 draw_char 166 draw_circle 166 draw_ellipse 166 draw_image 167 draw_string 166 dump_image 167 dup 179 dup2 179 elements 158 empty 153 157 Empty exception 156 159 End_of_file exception 122 end_of_stream 131 Index to the library environment 173 eprint 155 eprintf 147 155 eq module 115 eq_float 118 eq_int 120 eq_num 193 eq_string 133 equal 158 err_formatter 145 error_message 173 establish_server 187 exc module 116 except 129 exceptq 129 exec
68. 60 s_ixall 160 s_ixgrp 160 s_ixoth 160 s_ixusr 160 search_backward 198 search_forward 198 seek_in 127 seek_out 125 select 181 send 187 sendto 187 214 set 148 set module 157 set_approx_printing 195 set_color 165 set_ellipsis_text 144 set_error_when_null_denominator 194 set_floating_precision 195 set_font 166 set_formatter_out_channel 144 set_formatter_output_functions 144 set_line_width 166 set_margin 142 set_max_boxes 143 set_max_indent 143 set_normalize_ratio 195 set_normalize_ratio_when_printing 195 set_nth_char 132 set_print_depth 57 set_print_length 57 set_tab 144 set_text_size 166 setgid 184 setuid 184 shutdown 186 shutdown_connection 187 sign_num 193 signal 182 sin 118 sinh 118 size_x 165 size_y 165 sleep 183 snd 130 socket 186 socketpair 186 sort 158 sort module 158 sound 169 split 130 139 199 sprintf 155 sqrt 118 square_num 192 stack module 159 stat 148 177 std_err 122 std_formatter 145 std_in 122 std_out 122 stderr 122 175 stdin 122 175 stdout 122 175 str module 197 stream module 131 stream_check 131 stream_from 131 stream_get 131 stream_next 131 stream_of_channel 131 stream_of_string 131 string module 132 string_after 200 string_before 200 string_for_read 133 string_length 132 string_match 198 string_of_bool 114 string_of_char 115 string_of_float 119 string_of_ine
69. ON restarts output TCIOFF transmits a STOP character to suspend input and TCION transmits a START character to restart input Chapter 17 The num library arbitrary precision rational arithmetic The num library distributed in contrib libnum implements exact precision rational arithmetic It is built upon the state of the art BigNum arbitrary precision integer arithmetic package and therefore achieves very high performance The functions provided in this library are fully documented in The CAML Numbers Refer ence Manual by Val rie M nissier Morain technical report 141 INRIA july 1992 available by anonymous FTP from ftp inria fr directory INRIA publications RT file RT 0141 ps Z A summary of the functions is given below Programs that use the num library must be linked in custom runtime mode as follows camlc custom other options nums zo other files lnums For interactive use of the num library run camllight camlnum Mac This library is not available PC This library is available by default in the standard runtime system and in the toplevel system Programs that use this library can be linked normally without the custom option 17 1 num operations on numbers Numbers type num are arbitrary precision rational numbers plus the special elements 1 0 infinity and 0 0 undefined type num Int of int Big_int of big_int Ratio of ratio The type of numbers value normalize_num num gt num value nume
70. ORT EADDRINUSE EADDRNOTAVAIL ENETDOWN ENETUNREACH ENETRESET ECONNABORTED ECONNRESET ENOBUFS EISCONN Not enough core Permission denied Bad address Block device required Mount device busy File exists Cross device link No such device Not a directory Is a directory Invalid argument File table overflow Too many open files Not a typewriter Text file busy File too large No space left on device Illegal seek Read only file system Too many links Broken pipe Argument too large Result too large Operation would block Operation now in progress Operation already in progress Socket operation on non socket Destination address required Message too long Protocol wrong type for socket Protocol not available Protocol not supported Socket type not supported Operation not supported on socket Protocol family not supported Address family not supported by protocol family Address already in use Can t assign requested address Network is down Network is unreachable Network dropped connection on reset Software caused connection abort Connection reset by peer No buffer space available Socket is already connected
71. Set stdlib My HD Caml Light lib Troubleshooting Here is one commonly encountered problem Cannot find file stream zi Displayed in the Caml Light output window with an alert box telling you that Caml Light has terminated abnormally This is an installation error The folder named lib in the distribution must always be in the same folder as the Caml Light application It s OK to move the application to another folder but remember to move the lib directory to the same folder To return to the Finder first select Quit from the File menu 1 3 The MS Windows version Requirements A PC equipped with a 80386 80486 or Pentium processor running MS Windows 3 x Windows 95 or Windows NT About 3M of free space on the disk At least 8M of RAM is recommended Installation The MS Windows version is distributed as a self extracting self installing archive named cl74win exe Simply run it and follow the steps of the installation program Part II The Caml Light language reference manual Chapter 2 The core Caml Light language Foreword This document is intended as a reference manual for the Caml Light language It lists all 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 the language as provided by the companion tutorial Functional programming using Caml Light is assumed
72. The Caml Light system release 0 74 Documentation and user s manual Xavier Leroy December 2 1997 Copyright 1997 Institut National de Recherche en Informatique et Automatique Contents I Getting started 1 Installation instructions II 1 1 1 2 1 3 The Unix version 1 a The Macintosh version 0 a The MS Windows version 2 0 ce a The Caml Light language reference manual The core Caml Light language 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 2 10 2 11 Lexical conventions 2 Global names 2 1 a Values 6 a Type expressions o oo ee Constants oaoa a Patterns aaa Expressions oaoa Global definitions 2 ooa a Directives aoaaa aa ee Module implementations o aooaa a Module interfaces ooo a Language extensions 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 3 10 Streams parsers and printers 2 2 ee Guards 2 ee Range patterns 2 a Recursive definitions of values oaoa ee Local definitions using where aoaaa a ee Mutable variant types oaoa a String access oaoa Alternate syntax aooaa Infix symbols aa aaa Directives aoaaa a III The Caml Light commands 43 4 Batch compilation camlc 45 4 1 Overview of the compiler aoao aaa ee 45 4 2 Options 2 ee 46 4 3 Modules and the file system 2 2 0 0 0 02 020 eee eee eee 49 4 4 Common errors 2 ee 49 5 The toplevel system camllight 53 5 1 Options aoaaa e 54 5 2 Toplev
73. _int int gt int gt int Subtraction value prefix int gt int gt int value mult_int int gt int gt int Multiplication value prefix int gt int gt int value div_int int gt int gt int value prefix quo int gt int gt int Integer division Raise Division_by_zero if the second argument is 0 Give unpredictable results if either argument is negative value prefix mod int gt int gt int Remainder Raise Division_by_zero if the second argument is 0 Give unpredictable results if either argument is negative value eq_int int gt int gt bool Integer equality Equivalent to generic equality just faster value neq_int int gt int gt bool Negation of eq_int Chapter 13 The core library value lt_int int gt int gt bool value gt_int int gt int gt bool value le_int int gt int gt bool value ge_int int gt int gt bool Usual comparisons between integers value abs int gt int Return the absolute value of the argument value max_int int value min_int int The greatest and smallest integer values Bitwise operations value prefix land int gt int gt int Bitwise logical and value prefix lor int gt int gt int Bitwise logical or value prefix lxor int gt int gt int Bitwise logical exclusive or value lnot int gt int Bitwise complement value prefix lsl int gt int gt int value lshif
74. a gt int gt a contents gt a contents gt at gt at General insertion modification deletion function modify f g t searchs t for an element x satisfying the ordering function f If one is found g is applied to Something x if g returns Nothing the element x is removed if g returns Something y the element y replaces x in the tree It is assumed that x and y are equivalent in particular that f y is 0 If the tree does not contain any x satisfying f g is applied to Nothing if it returns Nothing the tree is returned unchanged if it returns Something x the element x is inserted in the tree It is assumed that f x is 0 The functions add and remove are special cases of modify slightly more efficient value split a gt int gt at gt a t a contents at split f t returns a triple less elt greater where less is a tree containing all elements x of t such that f x is negative greater is a tree containing all elements x of t such that f x is positive and elt is Something x if t contains an element x such that f x is 0 and Nothing otherwise value compare a gt a gt int gt at gt a t gt int Compare two trees The first argument f is a comparison function over the tree elements f e1 e2 is zero if the elements e1 and e2 are equal negative if e1 is smaller than e2 and positive if e1 is greater than e2 compare f t1 t2 compares the fringes of t1 and t2 by le
75. a in the list 1 value assq a gt a b list gt b Same as assoc but use physical equality instead of structural equality to compare keys value mem_assoc a gt a b list gt bool Same as assoc but simply return true if a binding exists and false if no bindings exist for the given key 130 13 13 pair operations on pairs value fst a b gt a Return the first component of a pair value snd a b gt b Return the second component of a pair value split a b list gt a list b list Transform a list of pairs into a pair of lists split a1 b1 Can bn is Lat an bi bn value combine a list b list gt a b list Transform a pair of lists into a list of pairs combine a1 an b1 bn is al b1 Can bn Raise Invalid_argument combine if the two lists have different lengths value map_combine a b gt c gt a list b list gt c list map_combine f a1 an b1 bn is f at b1 f Can bn Raise invalid_argument map_combine if the two lists have different lengths value do_list_combine a b gt unit gt a list b list gt unit do_list_combine f ai an b1 bn calls in turn f al b1 f an bn discarding the results Raise Invalid_argument do_list_combine if the two lists have d
76. ading 205 e Michael J Gordon Arthur J Milner and Christopher P Wadsworth Edinburgh LCF Lecture Notes in Computer Science volume 78 Springer Verlag 1979 This is the first published description of the ML language at the time when it was nothing more than the control language for the LCF system a theorem prover This book is now obsolete since the ML language has much evolved since then but it is still of historical interest e Paul Hudak Simon Peyton Jones and Philip Wadler Report on the programming language Haskell version 1 1 Technical report Yale University 1991 Haskell is a purely functional language with lazy semantics that shares many important points with ML full functionality polymorphic typing but has interesting features of its own dynamic overloading also called type classes 19 3 Implementing functional programming languages The references below are intended for those who are curious to learn how a language like Caml Light is compiled and implemented e Xavier Leroy The ZINC experiment an economical implementation of the ML language Technical report 117 INRIA 1990 Available by anonymous FTP on ftp inria fr A description of the ZINC implementation the prototype ML implementation that has evolved into Caml Light Large parts of this report still apply to the current Caml Light system in particular the description of the execution model and abstract machine Other parts are now obsolete Yet this
77. aking it possible to print or trace them The zix file is not produced if the implementation file has no explicit interface since in this case the module has no local values Cause the compiler to print the declared types exceptions and global variables with their inferred types when compiling an implementation ml file This can be useful to check the types inferred by the compiler Also since the output follows the syntax of module interfaces it can help in writing an explicit interface mli 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 globals I directory Add the given directory to the list of directories searched for compiled interface files zi and compiled object code files zo By default the current directory is searched first then the standard library directory Directories added with I are searched after the current directory but before the standard library directory When several directories are added with several I options on the command line these directories are searched from right to left the rightmost directory is searched first the leftmost is searched last Directories can also be added to the search path from inside the programs with the directory directive see chapter 3 lang language code Translate the compiler messages to the specified language The language code is fr for French es for Spa
78. alize_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 value get_normalize_ratio_when_printing unit gt bool value 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 value get_approx_printing unit gt bool value 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 value get_floating_precision unit gt int value set_floating_precision int gt unit Get or set the parameter floating_precision This parameter is the number of digits displayed when approx_printing is on Initially 12 196 Chapter 18 The str library regular expressions and string processing The str library distributed in contrib libstr 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 in custom runtime mode as follows camlc custo
79. allocated in the major heap including the promoted words minor_collections Number of minor collections major_collections Number of major collection cycles not counting the current cycle heap_words Total size of the major heap in words heap_chunks Number of times the major heap size was increased live_words Number of words of live data in the major heap including the header words live_blocks Number of live objects in the major heap free_words Number of words in the free list free_blocks Number of objects in the free list largest_words Size in words of the largest object in the free list fragments Number of wasted words due to fragmentation These are 1 words free blocks placed between two live objects They cannot be inserted in the free list thus they are not available for allocation 148 The total amount of memory allocated by the program 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 mutable major_heap_increment int mutable space_overhead int mutable verbose bool The GC parameters are given as a control record The fields are minor_heap_size The size in words of the minor heap Changing this parameter will trigger a minor collection major_heap_increment The minimum number of words to add to the major heap when increasing it space_overhead Th
80. ally selects the currently executing frame and describes it briefly as the frame command does Chapter 9 The debugger camldebug 85 frame Describe the currently selected stack frame frame 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 9 7 Examining variable values The debugger can print the current value of a program variable either a global variable or a local variable relative to the selected stack frame It can also print selected parts of a value by matching it against a pattern Variable names can be specified either fully qualified module name__var name or unqualified var name Unqualified names either correspond to local variables or are completed into full
81. alue 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 value set_color color gt unit Set the current drawing color value black color value white color value red color value green color value blue color value yellow color value cyan color value magenta color Some predefined colors value background color value foreground color Default background and foreground colors usually either black foreground on a white background or white foreground on a black background clear_graph fills the screen with the background color The initial drawing color is foreground 166 Point and line drawing value plot int gt int gt unit Plot the given point with the current drawing color value point_color int gt int gt color Return the color of the given point value moveto int gt int gt unit Position the current point value current_point unit gt int int Return the position of the current point value 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 value 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 ang
82. ame 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 type 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 Caml Light compiler unless the s option is in effect The type part is an arbitrary Caml Light 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 4token declaration is copied to both left symbol symbol Avight symbol symbol 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 4left right or Anonassoc line They have lower precedence than symbols declared after in a left 4right or fnonassoc line The symbols are declared to associate to the left left to the right Aright or to be non associative An
83. ameter to lhs_start and lhs_end n is 1 for the leftmost item value 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 14 11 printexc a catch all exception handler value f a gt b gt a gt b printexc__f 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 programs aborts with exit code 2 Typical use is printexc__f main where main with type unit gt unit is the entry point of a standalone program to catch and print stray exceptions For printexc__f to work properly the program must have been linked with the g option 14 12 printf formatting printing functions type a b c format The type of format strings a is the type of the parameters of the string c is the result type for the printf style function and b is the type of the first argument given to ha and 4t printing functions value fprintf out_channel gt a out_channel unit format gt a fprintf outchan format argi argN formats the arguments arg1 to argN according to the format string format and ou
84. annel gt int Same as input_char but return the 8 bit integer representing the character Raise End_of_file if an end of file was reached value input_binary_int in_channel gt int Read an integer encoded in binary format from the given input channel See output_binary_int Raise End_of_file if an end of file was reached while reading the integer value input_value in_channel gt a Read the representation of a structured value as produced by output_value or output_compact_value and return the corresponding value This is not type safe The type of the returned object is not a properly speaking the returned object has one unique type which cannot be determined at compile time The programmer should explicitly give the expected type of the returned value using the following syntax C input_value chan type The behavior is unspecified if the object in the file does not belong to the given type value 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 value pos_in in_channel gt int Return the current reading position for the given channel value in_channel_length in_channel gt int Return the total length number of characters of the given channel This works only for regular files On files of other kinds the result is meaningless value close_in
85. annel gt string gt int gt int gt int 4 input Primitives with several arguments are always curried The C function does not necessarily have the same name as the ML function Values thus declared primitive in a module interface must not be implemented in the module implementation the ml file They can be used inside the module implementation 12 1 2 Implementing primitives User primitives with arity n lt 5 are implemented by C functions that take n arguments of type value and return a result of type value The type value is the type of the representations for Caml Light values It encodes objects of several base types integers floating point numbers strings as well as Caml Light 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 value input channel buffer offset length value channel buffer offset length 99 100 When the primitive function is applied in a Caml Light 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 Light program as the result of the function application User primitives with arity greater than 5 are implemented by C functions that receive two arguments a pointer to an array of Caml Light values the va
86. anual Caml Light supports a certain class of recursive definitions of non functional values For instance the following definition is accepted let rec x 1 y andy 2 x and correctly binds x to the cyclic list 1 2 41 2 and y to the cyclic list 2 1 2 41 Informally the class of accepted definitions consists of those definitions where the defined variables occur only inside function bodies or as a field of a data structure Moreover the patterns in the left hand sides must be identifiers nothing more complex 3 5 Local definitions using where A postfix syntax for local definitions is provided expr n expr where rec let binding The expression expr where let binding behaves exactly as let let binding in expr and similarly for where rec and let rec 3 6 Mutable variant types The argument of a value constructor can be declared mutable when the variant type is defined type foo A of mutable int B of mutable int int This allows in place modification of the argument part of a constructed value Modification is performed by a new kind of expressions written ident lt expr where ident is an identifier bound by pattern matching to the argument of a mutable constructor and expr denotes the value that must be stored in place of that argument Continuing the example above 38 let x A iin begin match x with Ay gt y lt 2 x gt end returns the value A 2 The notation ident lt
87. arbage 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 Contents of the block 0 to No_scan_tag 1 A structured block an array of Caml Light objects Each field is a value Closure_tag A closure representing a functional value The first word is a pointer to a piece of bytecode the second word is a value containing the environment String_tag A character string Double_tag A double precision floating point number Abstract_tag A block representing an abstract datatype Final_tag A block representing an abstract datatype with a finaliza tion function to be called when the block is deallocated 12 2 3 Pointers to outside the heap Any pointer to outside the heap can be safely cast to and from the type value This includes pointers returned by malloc and pointers to C variables obtained with the amp operator
88. art the toplevel Or use load instead of load_object to load the source code instead of a compiled object file If filename has the format mod ml1 this means load or include could not find the specified source file Fix check the spelling of the file name or write it if it does not exist mod__name is referenced before being defined You have neglected to load in memory an implementation for a module with load or load_object This is explained in full detail in section 5 3 above Corrupted compiled interface file filename See section 4 4 Expression of type h cannot be used with type t See section 4 4 The type inferred for the value name that is t contains type variables that cannot be generaliz See section 4 4 5 5 Building custom toplevel systems camlmktop The camlmktop command builds Caml Light toplevels that contain user code preloaded at start up Mac This command is not available in the Macintosh version The camlmktop command takes as argument a set of zo files and links them with the object files that implement the Caml Light toplevel The typical use is camlmktop o mytoplevel foo zo bar zo gee zo This creates the bytecode file mytoplevel containing the Caml Light toplevel system plus the code from the three zo files To run this toplevel give it as argument to the camllight command camllight mytoplevel This starts a regular toplevel loop except that the code from foo zo bar zo and gee zo is already l
89. at value log float gt float value logi0 float gt float value sin float gt float value sinh float gt float value sqrt float gt float value tan float gt float value tanh float gt float Usual transcendental functions on floating point numbers value ceil float gt float value 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 Chapter 13 The core library 119 value abs_float float gt float Return the absolute value of the argument value mod_float float gt float gt float fmod a b returns the remainder of a with respect to b value 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 n value ldexp float gt int gt float ldexp x n returns x 2 n value modf float gt float float modf f returns the pair of the fractional and integral part of f value string_of_float float gt string Convert the given float to its decimal representation value float_of_string string gt float Convert the given string to a float in decimal The result is unspecified if the given string is not a valid representation of a float 13 8 fstring string o
90. ated by the inferior toplevel as usual The phrase is delimited by as described for the caml mark phrase command C c C r function caml eval region Send the region to a Caml toplevel running in an inferior process 11 3 Running the toplevel as an inferior process M x run caml starts a Caml toplevel with input and output in an Emacs buffer named inferior caml This gives you the full power of Emacs to edit the input to the Caml toplevel An history of input lines is maintained as in Shell mode This includes the following commands see the function comint mode for a complete description RET Send the current line to the toplevel M n and M p Move to the next or previous line in the history M r and M s Regexp search in the history C c C c Send a break interrupt signal to the Caml toplevel Phrases can also be sent to the Caml toplevel for evaluation from any buffer in Caml mode using M C x C c C e or C c C r Chapter 11 Using Caml Light under Emacs 97 11 4 Running the debugger as an inferior process The Caml debugger is started 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 prog
91. b1 f an bn Raise Invalid_argument map2 if the two lists have different lengths value do_list2 a gt b gt unit gt a list gt b list gt unit do_list2 f Lal an b1 bn calls in turn f a1 b1 f an bn discarding the results Raise Invalid_argument do_list2 if the two lists have different lengths value it_list2 a gt b gt c gt a gt a gt b list gt c list gt a it_list2 f a bi bn c1 cn is f f a bi c1 b2 c2 bn cn Raise Invalid_argument it_list2 if the two lists have different lengths value list_it2 a gt b gt c gt c gt a list gt b list gt c gt c list_it2 f ai an bi bn cis f a1 b1 f a2 b2 f an bn c Raise Invalid_argument list_it2 if the two lists have different lengths Chapter 13 The core library 129 value flat_map a gt b list gt a list gt b list flat_map f 11 ln is 11 f 12 f 1n value for_all a gt bool gt a list gt bool for_all p at an is p al amp p a2 amp amp p an value exists a gt bool gt a list gt bool exists p Lat an is p al or p a2 or or p an value mem a gt a list gt bool mem a 1 is true if and only if a is structurally equal see module eq to an element of 1 value memg
92. calls external functions written in C in default runtime mode As explained in chapter 12 such code must be linked in custom runtime mode Fix add the custom option as well as the native code libraries and native code object files that implement the required external functions Chapter 5 The toplevel system camllight This chapter describes the toplevel system for Caml Light that permits interactive use of the Caml Light system through a read eval print loop In this mode the system repeatedly reads Caml Light 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 A phrase can span several lines Phrases are delimited by the final double semicolon From the standpoint of the module system all phrases entered at toplevel are treated as the implementation of a module named top Hence all toplevel definitions are entered in the module top Unix The toplevel system is started by the command camllight Phrases are read on standard Mac input results are printed on standard output errors on standard error End of file on standard input terminates camllight see also the quit system function below The toplevel system does not perform line editing but it can easily be used in conjunction with an external line editor such as fep just run fep emacs camllight or fep vi camlli
93. chings fails the exception Match_failure is raised An alternate syntax is provided to bind variables to functional values instead of writing ident fun pattern pattern gt expr in a let expression one may instead write ident pattern pattern expr Both forms bind ident to the curried function with m arguments and only one case pattern pattern gt expr Recursive definitions of variables are introduced by let rec let rec pattern expr and and pattern expr in expr The only difference with the let construct described above is that the bindings of variables 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 consist in a single variable as in let rec ident fun and and ident fun in expr This defines ident ident as mutually recursive functions local to expr The behavior of other forms of let rec definitions is implementation dependent 2 7 2 Control constructs Sequence The expression expr expr evaluates expr fir
94. cimal radix 10 The following prefixes select a different radix hexadecimal radix 16 octal radix 8 binary radix 2 The initial O is the digit zero the 0 for octal is the letter O Floating point literals float literal 0 9 0 9 e E 0 9 7 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 Chapter 2 The core Caml Light language 15 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 Character literals 4 4 char literal regular char NAL Ent fr 0 9 0 9 0 9 Character literals are delimited by backquote characters The two backquotes enclose either one character different from and or one of the escape sequences below Character denoted backslash backquote newline LF return CR horizontal tabulation TAB backspace BS the character with ASCII code ddd in decimal String literals string literal string character regular char VV nf t b x 0 9 0 9 0 9 string character String literals are delimited by double quo
95. ck SIGTERM software termination signal from kill SIGURG urgent condition on IO channel SIGSTOP sendable stop signal not from tty SIGTSTP stop signal from tty SIGCONT continue a stopped process SIGCHLD to parent on child stop or exit SIGIO input output possible signal SIGXCPU exceeded CPU time limit SIGXFSZ exceeded file size limit SIGVTALRM virtual time alarm SIGPROF profiling time alarm SIGWINCH window changed SIGLOST resource lost eg record lock lost SIGUSR1 user defined signal 1 SIGUSR2 user defined signal 2 The type of signals type signal_handler Signal_default Default behavior for the signal Signal_ignore Ignore the signal Signal_handle of unit gt unit Call the given function when the signal occurs The behavior on receipt of a signal value kill int gt signal gt unit Send a signal to the process with the given process id value signal signal gt signal_handler gt unit Set the behavior to be taken on receipt of the given signal value pause unit gt unit Wait until a non ignored 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 fo
96. code interpreter the memory manager and the standard primitives e libraries and object code files o files mentioned on the command line for the Caml Light linker that provide implementations for the user s primitives This builds a runtime system with the required primitives The Caml Light linker generates byte code 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 camlc command with e the custom option e the names of the desired Caml Light object files zo files e the names of the C object files and libraries o and a files that implement the required primitives Libraries can also be specified with the usual 1 syntax 12 2 The value type All Caml Light objects are represented by the C type value defined in the include file mlvalues h along with macros to manipulate values of that type An object of type value is either e an unboxed integer 102 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 pointer to a block allocated by malloc or to a C variable 12 2 1 Integer values Integer values encode 31 bit signed integers They are unboxed unallocated 12 2 2 Blocks Blocks in the heap are g
97. ct v start len returns a fresh vector of length len containing the elements number start to start len 1 of vector v Raise Invalid_argument sub_vect if start and len do not designate a valid subvector of v that is if start lt 0 or len lt 0 or start len gt vect_length v value copy_vect a vect gt a vect copy_vect v returns a copy of v that is a fresh vector containing the same elements as v Chapter 13 The core library 135 value fill_vect a vect gt int gt int gt a gt unit fill_vect v ofs len x modifies the vector v in place storing x in elements number ofs to ofs len 1 Raise Invalid_argument fill_vect if ofs and len do not designate a valid subvector of v value blit_vect a vect gt int gt a vect gt int gt int gt unit blit_vect v1 o1 v2 o2 len copies len elements from vector v1 starting at element number o1 to vector v2 starting at element number o2 It works correctly even if vi and v2 are the same vector and the source and destination chunks overlap Raise Invalid_argument blit_vect if o1 and len do not designate a valid subvector of v1 or if o2 and len do not designate a valid subvector of v2 value list_of_vect a vect gt a list list_of_vect v returns the list of all the elements of v that is v 0 v 1 v vect_length v 1 value vect_of_list a list gt a vect vect_of_list 1 returns a fresh vector containing
98. ction keyword instead of fun function pattern gt expr pattern gt expr The function thus defined behaves exactly as described above The only difference between the two forms of function definition is how a parsing ambiguity is resolved The two forms cconstr pattern two patterns in a row and ncconstr pattern one pattern cannot be distinguished syntactically Function definitions introduced by fun resolve the ambiguity to the former form function definitions introduced by function resolve it to the latter form the former form makes no sense in this case Function application Function application is denoted by juxtaposition of expressions The expression expr eXpry expr evaluates the expressions expr to expr The expression expr must evaluate to a functional value which is then applied to the values of expry expr The order in which the expressions expr expr are evaluated is not specified Local definitions The let and let rec constructs bind variables locally The construct Chapter 2 The core Caml Light language 25 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 mat
99. d 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 Chapter 9 The debugger camldebug 89 set smallstep count Set the number of events between two checkpoints for small displacements The 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 9 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 90 Chapter 10 Profiling camlpro This chapter describes how the execution of Caml Light programs can be profiled by recording how many times functions are called branches of conditionals are taken Mac This command is
100. d of the string is reached value create_lexer 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 camllex is bound to the lexer buffer passed to the parsing function value get_lexeme lexbuf gt string get_lexeme lexbuf returns the string matched by the regular expression value get_lexeme_char lexbuf gt int gt char get_lexeme_char lexbuf i returns character number i in the matched string value get_lexeme_start lexbuf gt int get_lexeme_start lexbuf returns the position in the input stream of the first character of the matched string The first character of the stream has position 0 value get_lexeme_end lexbuf gt int get_lexeme_end lexbuf returns the position
101. d synonymous with begin e1 e2 end e Similarly an optional may begin a pattern matching expression For instance function pat gt expr is syntactically correct and synonymous with function pat gt expr e The tokens amp amp and are recognized as synonymous for amp sequential and and or sequen tial or respectively Chapter 3 Language extensions 39 3 9 Infix symbols Sequences of operator characters such as lt gt or are read as a single token from the infix symbol or prefix symbol class infix symbol lt gt 7 I amp operator char prefix symbol operator char operator char amp l 7 e s lt l gt 7 e cl tl Tokens from these two classes generalize the built in infix and prefix operators described in chap ter 2 expr n prefix symbol expr expr infix symbol expr variable prefix prefix symbol prefix infix symbol No infix directive section 3 10 is needed to give infix symbols their infix status The precedences and associativities of infix symbols in expressions are determined by their first character s symbols beginning with have highest precedence exponentiation followed by symbols beginning with or multiplication then and addition then and concatenation then all others symbols comparisons The updated precedence table for expressions is shown below We w
102. dence come first Chapter 2 The core Caml Light language 23 Construction or operator Associativity function application constructor application prefix comparisons not amp or gt lt if let match fun function try 2 7 1 Simple expressions Constants Expressions consisting in a constant evaluate to this constant Variables Expressions consisting in a variable evaluate to the value bound to this variable in the current evaluation environment The variable can be either a qualified identifier or a simple identifier Qualified identifiers always denote global variables Simple identifiers denote either a local variable if the identifier is locally bound or a global variable whose full name is obtained by qualifying the simple identifier as described in section 2 2 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 type This constraint forces the type of expr to be compatible with type 24 Function abstraction The most general form of function abstraction is fun patternt pattern gt expr pattern pattern gt expr This ex
103. dentation limit maximum number of boxes simultaneously opened ellipsis and so on are specific to each pretty printer and may be fixed independently A new formatter is obtained by calling the make_formatter function value std_formatter formatter The standard formatter used by the formatting functions above It is defined using make_formatter with output function output stdout and flushing function fun gt flush stdout value err_formatter formatter A formatter to use with formatting functions below for output to standard error It is defined using make_formatter with output function output stderr and flushing function fun gt flush stderr value 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 flushing function flush Hence a formatter to out channel oc is returned by make_formatter output oc fun gt flush oc value pp_open_hbox formatter gt unit gt unit value pp_open_vbox formatter gt int gt unit value pp_open_hvbox formatter gt int gt unit value pp_open_hovbox formatter gt int gt unit value pp_open_box formatter gt int gt unit value pp_close_box formatter gt unit gt unit value pp_print_string formatter gt string gt unit value pp_print_as formatter gt int gt string gt unit value pp_print_
104. descr value stderr file_descr File descriptors for standard input standard output and standard error type open_flag O_RDONLY Open for reading O_WRONLY Open for writing O_RDWR Open for reading and writing O_NDELAY 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 The flags to open type file_perm int The type of file access rights value open 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 176 value close file_descr gt unit Close a file descriptor value read file_descr gt string gt int gt int gt int read fd buff start len reads len characters from descriptor fd storing them in string buff starting at position ofs in string buff Return the number of characters actually read value write file_descr gt string gt int gt int gt int write fd buff start 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 Interfacing with the standard input output library module io value in_channel_of_descr file_descr gt in_channel Create an input channel readin
105. during the latest string_match search_forward or search_backward The user must make sure that the parameter s is the same string that was passed to the matching or searching function Chapter 18 The str library regular expressions and string processing 199 value group_beginning int gt int value group_end 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 group_end n returns the position of the character following the last character of the matched substring Replacement value global_replace regexp gt string gt string gt string global_replace regexp repl s returns a string identical to s except that all substrings of s that match regexp have been replaced by repl The replacement text repl can contain 1 2 etc these sequences will be replaced by the text matched by the corresponding group in the regular expression O stands for the text matched by the whole regular expression value replace_first regexp gt string gt string gt string Same as global_replace except that only the first substring matching the regular expression is replaced value 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 i
106. e gt color vect vect Convert an image to a color matrix value draw_image image gt int gt int gt unit Draw the given image with lower left corner at the given point 168 value 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 fill_rect value 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 value blit_image image gt int gt int gt unit blit_image img x y copies screen pixels into the image img modifying img 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 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 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 value wait_next_event event list gt s
107. e 188 gethostname 188 getlogin 184 getpeername 187 getpid 175 getppid 175 getprotobyname 188 getprotobynumber 188 getpwnam 185 getpwuid 185 getservbyname 188 getservbyport 188 getsockname 186 gettimeofday 183 getuid 184 global_replace 199 global_substitute 199 gmtime 183 Graphic_failure exception 164 graphics module 164 green 165 group_beginning 199 group_end 199 gt_float 118 gt_int 121 gt_num 193 gt_string 133 handle_unix_error 173 hash 151 hash_param 151 hashtbl module 150 hd 128 in_channel_length 127 in_channel_of_descr 176 include 56 incr 130 incr_num 193 index 129 index_char 133 index_char_from 133 inet_addr_of_string 185 init 157 init_vect 134 input 126 input_binary_int 127 input_byte 127 input_char 126 input_line 126 input_value 127 install_printer 57 int 157 int module 120 int_of_char 115 int_of_float 117 int_of_num 194 int_of_string 122 integer_num 192 inter 158 interactive 160 intersect 129 invalid_arg 116 Invalid_argument exception 116 io module 122 ioctl_int 180 ioctl_ptr 180 is_absolute 140 is_empty 157 is_integer_num 192 it_list 128 it_list2 128 iter 153 156 158 159 join 200 key_pressed 169 kill 182 land infix 121 last_chars 200 ldexp 119 le_float 118 Index to the library le_int 121 le_num 193 le_string 133 length 156 159 lexing module 151 lineto 166 lin
108. e equal or else 2 if s1 is a prefix of s2 or 2 if s2 is a prefix of s1 or else 1 if s1 is lexicographically before s2 or 1 if s2 is lexicographically before s1 value string_for_read string gt string Return a copy of the argument with special characters represented by escape sequences following the lexical conventions of Caml Light value index_char string gt char gt int index_char 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 value rindex_char string gt char gt int rindex_char 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 value index_char_from string gt int gt char gt int value rindex_char_from string gt int gt char gt int Same as index_char and rindex_char but start searching at the character position given as second argument index_char s c is equivalent to index_char_from s 0 c and rindex_char s c to rindex_char_from s string_length s 1 c 134 13 17 vect operations on vectors value vect_length a vect gt int Return the length number of elements of the given vector value vect_item a vect gt int gt a vect_item v n returns the element number n of vector v The first element has number 0 The last element has number vect_length v 1 Raise Invalid_argument vect_item if n is outside the range 0 to v
109. e that is intended to be executed with the shared runtime system camlrun 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 considerably larger but it can be executed directly even if the camlrun command is not installed Moreover the custom runtime mode enables linking Caml Light code with user defined C functions as described in chapter 12 Chapter 4 Batch compilation camlc 47 Unix Never strip an executable produced with the custom option PC This option requires the DJGPP port of the GNU C compiler to be installed Cause the compiler to produce additional debugging information During the linking phase this option add information at the end of the executable bytecode file produced This infor mation is required by the debugger camldebug and also by the catch all exception handler from the standard library module printexc During the compilation of an implementation file m1 file when the g option is set the compiler adds debugging information to the zo file It also writes a zix file that describes the full interface of the m1 file that is all types and values defined in the m1 file including those that are local to the ml file i e not declared in the mli interface file Used in conjunction with the g option to the toplevel system chapter 5 the zix file gives access to the local values of the module m
110. e major GC speed is computed from this parameter This is the percentage of heap space that will be wasted because the GC does not immediatly collect unreachable objects The GC will work more use more CPU time and collect objects more eagerly if space_overhead is smaller The computation of the GC speed assumes that the amount of live data is constant verbose This flag controls the GC messages on standard error output value stat unit gt stat Return the current values of the memory management counters in a stat record value print_stat lo__out_channel gt unit Print the current values of the memory management counters in human readable form into the channel argument value get unit gt control Return the current values of the GC parameters in a control record value set control gt unit set r changes the GC parameters according to the control record r The normal usage is let r gc__get in Get the current parameters r verbose lt true Change some of them gc__set r Set the new values value minor unit gt unit Trigger a minor collection Chapter 14 The standard library 149 value major unit gt unit Finish the current major collection cycle value full_major unit gt unit Finish the current major collection cycle and perform a complete new cycle This will collect all currently unreachable objects 14 6 genlex a generic lexical analyzer This module implemen
111. e mm expr2 e At the beginning of each iteration of a loop while cond do body done for i a to b do 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 Also no event is put after a function application when the function is a primitive function written in C Finally several events may correspond to the same location in the compiled program Then the debugger cannot distinguish them and selects one of the events to associate with the given code location The event chosen is a function application event if there is one at that location or otherwise the event which appears last in the source This heuristic generally picks the most interesting event associated with the code location 9 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 se
112. e position of the right margin Chapter 14 The standard library 143 Maximum indentation limit value set_max_indent int gt unit 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 or bigger than 999999999 value 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 value 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 not greater than 1 value get_max_boxes unit gt int Return the maximum number of boxes allowed before ellipsis value over_max_boxes unit gt bool Test the maximum number of boxes allowed have already been opened Advanced formatting value 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 value 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
113. e required precision The second argument is the number to approximate approx_fix uses decimal notation the first argument is the number of digits after the decimal point approx_exp uses scientific exponential notation the first argument is the number of digits in the mantissa value num_of_string string gt num Convert a string to a number Coercions between numerical types value int_of_num num gt int value num_of_int int gt num value nat_of_num num gt nat__nat value num_of_nat nat__nat gt num value num_of_big_int big_int gt num value big_int_of_num num gt big_int value ratio_of_num num gt ratio value num_of_ratio ratio gt num value float_of_num num gt float value num_of_float float gt num value sys_print_num int gt string gt num gt string gt unit value print_num num gt unit 17 2 arith_status flags that control rational arithmetic value arith_status unit gt unit Print the current status of the arithmetic flags value get_error_when_null_denominator unit gt bool value 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 Chapter 17 The num library arbitrary precision rational arithmetic 195 value get_normalize_ratio unit gt bool value set_norm
114. e section 9 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 Chapter 9 The debugger camldebug 83 9 4 3 Running the program The following commands execute the program 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 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 finish Run the program until the current function returns 9 4 4 Time travel You can jump directly to a given time wit
115. e t But the interface mod2 zi will still use the old stamp for mod1__t in the type of mod2__g Hence when compiling mod3 m1 the system complains that the argument type of mod2__g that is modi__t with the old stamp is not compatible with the type of mod1__A that is mod1__t with the new stamp Fix use make or a similar tool to ensure that all clients of a module mod are recompiled when the interface mod zi changes To check that the Makefile contains the right dependencies remove all zi files and rebuild the whole program if no Cannot find file error appears you re all set The type inferred for name that is t contains non generalizable type variables 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 is valid only for one instantiation of the variables In a Chapter 4 Batch compilation camlc 51 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 val
116. e used in toplevel phrases without having to load any zo file in memory e The interfaces for the modules below are 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 provided by these modules without adding open directives Actually the list of automatically opened modules depend on the 0 option given to the compiler or to the toplevel system Opened modules reverse opening order 0 cautious default io eq int float ref pair list vect char string bool exc stream builtin 0 fast io eq int float ref pair list fvect fchar fstring bool exc stream builtin 0 none builtin Conventions For easy reference the modules are listed below in alphabetical order of module names For each module the declarations from its interface file 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 13 1 bool boolean operations value prefix amp bool gt bool gt bool 113 114 value prefix amp amp bool gt bool gt bool value prefix or bool gt bool gt bool value prefix bool gt bool gt bool The boolean and is written e1 amp e2 or e1 amp amp e2 The boolean or is written e1 or e2 or e1 e2 Both constructs are sequential left to right e2 is evaluated o
117. e variables The type expression ident stands for the type variable named ident In data type definitions type variables are names for the data type parameters In type constraints they represent unspecified types that can be instantiated by any type to satisfy the type constraint Parenthesized types The type expression typexpr denotes the same type as typexpr Function types The type expression typexpr gt typexpr denotes the type of functions mapping arguments of type typexpr to results of type 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 20 2 5 Constants constant integer literal float literal char literal string literal cconstr The syntactic class of constants comprises literals from the four base types integers floating point numbers characters character strings and constant con
118. ecode executable files are bigger and take slightly longer to produce but the executable files run at exactly the same speed as if they had been compiled without g It is therefore perfectly acceptable to compile always in g mode 9 2 Invocation 9 2 1 Starting the debugger The Caml Light debugger is invoked by running the program camldebug with the name of the bytecode executable file as argument camldebug program The following command line options are recognized stdlib directory Look for the standard library files in directory instead of in the default directory 79 80 s socket Use socket for communicating with the debugged program See the description of the com mand set socket section 9 8 7 for the format of socket c count Set the maximum number of checkpoints to count cd directory Run the debugger program from the working directory directory instead of the current di rectory emacs Tell the debugger it is executing under Emacs See section 11 4 for information on how to run the debugger under Emacs 9 2 2 Quitting 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 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 9 3 Commands A debugger command is a single line of input I
119. ect_length v 1 You can also write v n instead of vect_item v n value vect_assign a vect gt int gt a gt unit vect_assign v n x modifies vector v in place replacing element number n with x Raise Invalid_argument vect_assign ifn is outside the range 0 to vect_length v 1 You can also write v n lt x instead of vect_assign v n x value make_vect int gt a gt a vect make_vect n x returns a fresh vector of length n initialized with x All the elements of this new vector are initially physically equal to x see module eq Consequently if x is mutable it is shared among all elements of the vector and modifying x through one of the vector entries will modify all other entries at the same time value make_matrix int gt int gt a gt a vect vect make_matrix dimx dimy e returns a two dimensional array a vector of vectors 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 mis accessed with the notation m x y value init_vect int gt int gt a gt a vect init_vect n f returns a fresh array of length n with element number i equal to f i value concat_vect a vect gt a vect gt a vect concat_vect vi v2 returns a fresh vector containing the concatenation of vectors v1 and v2 value sub_vect a vect gt int gt int gt a vect sub_ve
120. ed in modules other than the top module with the same mechanisms as for separately compiled modules either by using qualified identifiers modulename__localname or by using unqualified identifiers that are automatically completed by searching the list of opened modules See section 2 2 The modules opened at startup are given in the documentation for the standard library Other modules can be opened with the open directive However before referencing a global variable from a module other than the top module a definition of that global variable must have been entered in memory At start up the toplevel system contains the definitions for all the identifiers in the standard library The definitions for user modules can be entered with the load or load_object functions described above Referencing a global variable for which no definition has been provided by load or load_object results in the error Identifier foo__bar is referenced before being defined Since this is a tricky point let us consider some examples 1 The library function sub_string is defined in module string This module is part of the standard library and is one of the modules automatically opened at start up Hence both phrases sub_string qwerty 1 3 string__sub_string qwerty 1 3 are correct without having to use open load or load_object 2 The library function printf is defined in module printf This module is part of the standard library but it is
121. el control functions aoaaa a 55 5 3 The toplevel and the module system aoaaa aaa a 58 5 4 Common errors a oa ee 59 5 5 Building custom toplevel systems camlmktop ooa 60 5 6 Options aaa a 61 6 The runtime system camlrun 63 6 1 Overview a 63 6 2 Options 0 ee 64 6 3 Common errors oaoa ee 64 7 The librarian camllibr 67 7 1 Overview ee 67 7 2 Options 2 ee 68 7 3 Turning codeintoalibrary 2 0 0 00 00 002 0 eee eee eee 68 8 Lexer and parser generators camllex camlyacc 71 8 1 Overview of camllex 2 20 0 ee 71 8 2 Syntax of lexer definitions 2 2 20 20 0 0 00 ee ee ee 72 8 3 Overview of camlyacc 2 ee 74 8 4 Syntax of grammar definitions 2 00 00 0022 ee eee 74 8 5 Options 2 2 ee 76 8 6 A complete example 2 2 2 0 02 0 ee ee 76 9 The debugger camldebug 79 9 1 Compiling for debugging 2 2 2 2 2 0 0 00 a 79 9 2 Invocation sasaaa 79 9 3 Commands 0 ee 80 9 4 Executing a program aoaaa ee 81 9 5 Breakpoints 2 0 2 ee 84 9 6 The call stack 2 0 0 0 0 02 ee 84 9 7 Examining variable values naasa ee 85 9 8 Controlling the debugger 2 2 ee ee 86 9 9 Miscellaneous commands 0 2 0000 ee ee 89 10 Profiling camlpro 10 1 Compiling for profiling 2 2 0 0 0 2 00 00 0020 000000 10 2 Profiling an execution aoao ee 10 3 Printing profiling information 0 0 00 0 0000000004 10 4 Kn
122. ent expr is evaluated first The second component expr is not evaluated if the first component evaluates to true Hence the expression expr or expr behaves exactly as if expr then true else exprs Loops The expression while expr do expr done repeatedly evaluates expr while expr 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 ident expr to expr do exprs done first evaluates the expressions expr and expr the boundaries into integer values n and p Then the loop body exprs is repeatedly evaluated in an environment where the local variable named ident is successively bound to the values n n 1 p 1 p The loop body is never evaluated if n gt p The expression for ident expr downto expr do exprs done first evaluates the expressions expr and expr the boundaries into integer values n and p Then the loop body exprs is repeatedly evaluated in an environment where the local variable named ident is successively bound to the values n n 1 p 1 p The loop body is never evaluated if n lt p In both cases the whole for expression evaluates to the unit value Chapter 2 The core Caml Light language 27 Exception handling The expression try expr with pattern gt expr pattern gt expr evaluates the expression expr and returns its value if the evaluatio
123. eractive 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 of f the debugger will not take any checkpoints set checkpoints on off Select whether the debugger makes checkpoints or not 9 8 7 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 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 On the debugged program side the socket name is passed either by the D command line option to camlrun or through the CAML_DEBUG_SOCKET environment variable 9 8 8 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 han
124. es many Unix system calls and system related library functions available to Caml Light 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 in custom runtime mode as follows camlc custom other options unix zo other files lunix For interactive use of the unix library run camllight camlunix Mac This library is not available PC This library is not available 16 1 unix interface to the Unix system Error report type error ENOERR EPERM Not owner ENOENT No such file or directory ESRCH No such process EINTR Interrupted system call EIO I O error ENXIO No such device or address E2BIG Arg list too long ENOEXEC Exec format error EBADF Bad file number ECHILD No children EAGAIN No more processes 171 172 ENOMEM EACCES EFAULT ENOTBLK EBUSY EEXIST EXDEV ENODEV ENOTDIR EISDIR EINVAL ENFILE EMFILE ENOTTY ETXTBSY EFBIG ENOSPC ESPIPE EROFS EMLINK EPIPE EDOM ERANGE EWOULDBLOCK EINPROGRESS EALREADY ENOTSOCK EDESTADDRREQ EMSGSIZE EPROTOTYPE ENOPROTOOPT EPROTONOSUPPORT ESOCKTNOSUPPORT EOPNOTSUPP EPFNOSUPPORT EAFNOSUPP
125. es such as 150 let parse_expr function lt Intn gt gt n lt Kwd parse_expr n Kwd gt gt n lt parse_expr n1 parse_remainder n1 n2 gt gt n2 and parse_remainder ni function lt Kwd parse_expr n2 gt gt nitn2 14 7 hashtbl hash tables and hash functions Hash tables are hashed association tables with in place modification type Ca b t The type of hash tables from type a to type b value new int gt a b t new n creates a new empty hash table with initial size n The table grows as needed so n is just an initial guess Better results are said to be achieved when n is a prime number Raise Invalid_argument hashtbl__new if n is less than 1 value clear a b t gt unit Empty a hash table value add a b t gt a gt b gt unit 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 remove tbl x the previous binding for x if any is restored This is the semantics of association lists value find a b t gt a gt b find tbl x returns the current binding of x in tbl or raises Not_found if no such binding exists value find_all Ca b t gt a gt b list 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
126. escr gt sockaddr Return the address of the host connected to the given socket value recv file_descr gt string gt int gt int gt msg_flag list gt int value recvfrom file_descr gt string gt int gt int gt msg_flag list gt int sockaddr Receive data from an unconnected socket value send file_descr gt string gt int gt int gt msg_flag list gt int value sendto file_descr gt string gt int gt int gt msg_flag list gt sockaddr gt int Send data over an unconnected socket High level network connection functions value open_connection sockaddr gt in_channel out_channel Connect to a server at the given address Return a pair of buffered channels connected to the server Remember to call flush on the output channel at the right times to ensure correct synchronization value shutdown_connection in_channel gt unit Shut down a connection established with open_connection that is transmit an end of file condition to the server reading on the other side of the connection value establish_server in_channel gt 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 establish_server never returns normally Host and protocol databases type host_en
127. esponding to the four fields of the control record documented in section 14 5 s minor_heap_size Size of the minor heap i major_heap_increment Minimum size increment for the major heap space_overhead The major GC speed setting v verbose Whether to print GC messages or not 0 is false 1 is true other values may give unexpected results For example under csh the command setenv CAMLRUNPARAM s 250000 v 1 tells a subsequent camlrun to set its initial minor heap size to about 1 megabyte on a 32 bit machine and to print its GC messages PATH List of directories searched to find the bytecode executable file 6 3 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 camlrun bytecode interpreter on itself The second possibility indicates that Caml Light has not been properly installed on your system Cannot exec camlrun When launching a self executable bytecode file The camlrun command could not be found in the executable path Check that Caml Light has been properly installed on your system Cannot find the bytecode file The file that camlrun is trying to execute e g the file given as first non option argument to camlrun either does not exist or is not a valid executable bytecode file Chapter
128. essary 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 interface file 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 14 1 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 There are four types of keywords Unit String Int and Float Unit keywords do not take an argument String Int and Float keywords take the following word on the command line as an 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 137 138 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 1 2 3 three anonymous arguments 1 2 and 3 cmd 1 2 flag 3 string bar 4 four anonymous arguments a unit option and a string option with argument bar type spec String of string gt unit Int of int
129. ession label expr label expr evaluates to the record value label v label Vn where v is the value of expr for t 1 n The labels label to label must all belong to the same record types all labels belonging to this record type must appear exactly once in the record expression though they can appear in any order The order in which expr to expr are evaluated is not specified The expression expr label evaluates expr to a record value and returns the value associated to label in this record value The expression expr label lt expr evaluates expr to a record value which is then modified in place by replacing the value associated to label in this record by the value of expr This operation is permitted only if label has been declared mutable in the definition of the record type The whole expression expr label lt expr evaluates to the unit value 28 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 is equivalent to the application vect_item expr expr In the initial environment the identifier vect_item resolves to a built in function that 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
130. exbuf Where entrypoint is the name of another entry point in the same lexer definition Recursively call the lexer on the given entry point Useful for lexing nested comments for example 8 3 Overview of camlyacc The camlyacc command produces a parser from a context free grammar specification with attached semantic actions in the style of yacc Assuming the input file is grammar mly executing camlyacc options grammar mly produces Caml Light code for a parser in the file grammar m1 and its interface in file grammar m1i 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 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 camllex 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 camlyacc 8 4 Syntax of grammar definitions Grammar definitions have the following format ma header h declarations hh rules hh 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 tra
131. f the error messages are implementation dependent and should not be relied upon to catch specific system errors 160 value command_line string vect The command line arguments given to the process The first element is the command name used to invoke the program value interactive bool True if we re running under the toplevel system False if we re running as a standalone program type file_perm int value s_irusr file_perm value s_iwusr file_perm value s_ixusr file_perm value s_irgrp file_perm value s_iwgrp file_perm value s_ixgrp file_perm value s_iroth file_perm value s_iwoth file_perm value s_ixoth file_perm value s_isuid file_perm value s_isgid file_perm value s_irall file_perm value s_iwall file_perm value s_ixall file_perm Access permissions for files r is reading permission w is writing permission x is execution permission usr means permissions for the user owning the file grp for the group owning the file oth for others isuid and isgid are for set user id and set group id files respectively The remaining are combinations of the permissions above type open_flag O_RDONLY open read only O_WRONLY open write only O_RDWR open for reading and writing O_APPEND open for appending O_CREAT create the file if nonexistent O_TRUNC truncate the file to 0 if it exists O_EXCL fails if the file exists O_BINARY open in binar
132. f the name must be valid identifiers Externally global names have the following syntax global name ident ident __ ident The form ident __ ident is called a qualified name The first identifier is the module name the second identifier is the local name The form ident is called an unqualified name The identifier is the local name the module name is omitted The compiler infers this module name following the completion rules given below therefore transforming the unqualified name into a full global name To complete an unqualified identifier the compiler checks a list of modules the opened modules to see if they define a global with the same local name as the unqualified identifier When one is found the identifier is completed into the full name of that global That is the compiler takes as module name the name of an opened module that defines a global with the same local name as the unqualified identifier If several modules satisfy this condition the one that comes first in the list of opened modules is selected The list of opened modules always includes the module currently being compiled checked first In the case of a toplevel based implementation this is the module where all toplevel definitions are entered It also includes a number of standard library modules that provide the initial environment Chapter 2 The core Caml Light language 17 checked last In addition the open and close directives can be used to add o
133. function is therefore inserted in the output of fprintf at the current point t same as fa but takes only one argument with type out_channel gt unit and apply it to outchan Refer to the C library printf function for the meaning of flags and field width specifiers If too few arguments are provided printing stops just before converting the first missing argument value printf a out_channel unit format gt a Same as fprintf but output on std_out value eprintf a out_channel unit format gt a Same as fprintf but output on std_err value sprintf a unit string format gt a Same as fprintf except that the result of the formatting is returned as a string instead of being written on a channel value fprint out_channel gt string gt unit Print the given string on the given output channel without any formatting This is the same function as output_string of module io value print string gt unit Print the given string on std_out without any formatting This is the same function as print_string of module io value eprint string gt unit Print the given string on std_err without any formatting This is the same function as prerr_string of module io 156 14 13 queue queues This module implements queues FIFOs with in place modification type a t The type of queues containing elements of type a exception Empty Raised when take is applied to an empty queue
134. g from the given descriptor value out_channel_of_descr file_descr gt out_channel Create an output channel writing on the given descriptor value descr_of_in_channel in_channel gt file_descr Return the descriptor corresponding to an input channel value descr_of_out_channel out_channel gt file_descr Return the descriptor corresponding to an output channel Seeking and truncating type seek_command SEEK_SET SEEK_CUR SEEK_END Positioning modes for lseek SEEK_SET indicates positions relative to the beginning of the file SEEK_CUR relative to the current position SEEK_END relative to the end of the file value lseek file_descr gt int gt seek_command gt int Set the current position for a file descriptor value truncate string gt int gt unit Truncates the named file to the given size value ftruncate file_descr gt int gt unit Truncates the file corresponding to the given descriptor to the given size Chapter 16 The unix library Unix system calls File statistics type file_kind S_REG S_DIR S_CHR S_BLK S_LNK S_FIFO S_SOCK type stats st_dev int value stat value lstat value fstat Operations on file names value unlink value rename value link st_ino int st_kind file_kind st_perm file_perm st_nlink int st_uid int st_gid int st_rdev int st_size int st_atime int st_mtime int st_ctime int The information
135. ge for a complete description type terminal_io Input modes Chapter 16 The unix library Unix system calls 189 mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable mutable Output mutable c_ignbrk bool c_brkint bool c_ignpar bool c_parmrk bool c_inpck bool c_istrip bool c_inlcr bool c_igncr bool c_icrnl bool c_ixon bool c_ixoff bool modes c_opost bool Control modes mutable mutable mutable mutable mutable mutable mutable mutable mutable c_obaud int c_ibaud int c_csize int c_cstopb int c_cread bool c_parenb bool c_parodd bool c_hupcl bool c_clocal bool Local modes mutable mutable mutable mutable mutable mutable mutable c_isig bool c_icanon bool c_noflsh bool c_echo bool c_echoe bool c_echok bool c_echonl bool Control characters mutable mutable mutable mutable mutable mutable mutable c_vintr char c_vquit char c_verase char c_vkill char c_veof char c_veol char c_vmin int Ignore the break condition Signal interrupt on break condition Ignore characters with parity errors Mark parity errors Enable parity check on input Strip 8th bit on input characters Map NL to CR on input
136. ght Another option is to use camllight under Gnu Emacs which gives the full editing power of Emacs see the directory contrib camlmode in the distribution At any point the parsing compilation or evaluation of the current phrase can be inter rupted by pressing ctr1 C or more precisely by sending the intr signal to the camllight process This goes back to the prompt The toplevel system is presented as the standalone Macintosh application Caml Light This application does not require the Macintosh Programmer s Workshop to run Once launched from the Finder the application opens two windows Caml Light Input and Caml Light Output Phrases are entered in the Caml Light Input window The Caml Light Output window displays a copy of the input phrases as they are processed by the Caml Light toplevel interspersed with the toplevel responses The Return key sends the contents of the Input window to the Caml Light toplevel The Enter key inserts a newline without sending the contents of the Input window This can be configured with the Preferences menu item The contents of the input window can be edited at all times with the standard Macintosh interface An history of previously entered phrases is maintained and can be accessed with the Previous entry command P and Next entry command N menu items 53 54 PC 5 1 To quit the Caml Light application either select Quit
137. gt int gt unit and The implementation of the mylib module simply equates the abstract types and the public functions to the corresponding types and functions in the modules windows images and buttons Chapter 7 The librarian camllibr 69 File mylib ml type window windows__win and image images__pixmap and button buttons__t let new_window windows__open_window and draw_image images__draw and The files windows ml images ml and buttons ml can open the mylib module to access the public types defined in the interface mylib m1li such as the option type Of course these modules must not reference the abstract types nor the public functions to avoid circularities Types such as windows__win in the example above can be exported by the windows module either abstractly or concretely with their definition Often it is necessary to export them con cretely because the other modules in the library images buttons need to build or destructure directly values of that type Even if windows__win is exported concretely by the windows module that type will remain abstract to the library user since it is abstracted by the public interface mylib The actual building of the library mylib proceeds as follows camlc c mylib mli create mylib zi camlc c windows mli windows ml images mli images ml camlc c buttons mli buttons ml camlc c mylib ml create mylib zo mv mylib zo tmplib zo renaming to avoid over
138. guish between text mode and binary mode this function behaves like open_out value open_out_gen sys__open_flag list gt int gt string gt out_channel open_out_gen mode rights filename opens the file named filename for writing as above The extra argument mode specify the opening mode see sys__open The extra argument rights specifies the file permissions in case the file must be created see sys__open open_out and open_out_bin are special cases of this function value open_descriptor_out int gt out_channel open_descriptor_out fd returns a buffered output channel writing to the file descriptor fd The file descriptor fd must have been previously opened for writing else the behavior is undefined value 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 std_out and std_err at the right time Chapter 13 The core library 125 value output_char out_channel gt char gt unit Write the character on the given output channel value output_string out_channel gt string gt unit Write the string on the given output channel value output out_channel gt string gt int gt int gt unit output chan buff ofs len writes len characters from string buff starting at offset ofs to the output channel chan Raise Invalid_argument output if ofs and len do not designate a valid
139. guments the character strings arg to arg See chapter 6 for more details Unix On most Unix systems the file produced by the linking phase can be run directly as in caml out arg arg arg The produced file has the executable bit set and it manages to launch the bytecode inter preter by itself PC The output file produced by the linking phase is directly executable provided it is given extension EXE Hence if the output file is named caml_out exe you can execute it with the command caml_out arg arg arg Actually the produced file caml_out exe is a tiny executable file prepended to the bytecode file The executable simply runs the camlrun runtime system on the remainder of the file As a consequence this is not a standalone executable it still requires camlrun exe to reside in one of the directories in the path 4 2 Options The following command line options are recognized by camlc 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 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 bytecod
140. hannels opened by open_process_in open_process_out and open_process respectively wait for the associated command to terminate and return its termination status Symbolic links value symlink string gt string gt unit symlink source dest creates the file dest as a symbolic link to the file source value readlink string gt string Read the contents of a link Named pipes value mkfifo string gt file_perm gt unit Create a named pipe with the given permissions Special files value ioctl_int file_descr gt int gt int gt int Interface to ioctl in the case where the argument is an integer The first integer argument is the command code the second is the integer parameter value ioctl_ptr file_descr gt int gt string gt int Interface to ioctl in the case where the argument is a pointer The integer argument is the command code A pointer to the string argument is passed as argument to the command Chapter 16 The unix library Unix system calls 181 Polling value 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
141. he resulting phrase may require large amounts of memory to be compiled by Caml Light With the s option the vector of actions is constructed incrementally one phrase per action This lowers the memory requirements for the compiler but it is no longer possible to infer the types of nonterminal symbols typechecking is turned off on symbols that do not have a type specified by a type directive bprefix Name the output files prefiz ml prefix mli prefiz output instead of the default naming convention 8 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 Chapter 8 Lexer and parser generators camllex camlyacc 77 token LPAREN RPAREN Atoken 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 hh 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 mll open parser The type token is defined in parser mli exception Eof rule Token
142. hout 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 step 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 9 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 84 9 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 for further reference 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 Moreover C functions are not recognized
143. ifferent lengths 13 14 ref operations on references type a ref ref of mutable a The type of references mutable indirection cells containing a value of type a value prefix a ref gt a r returns the current contents of reference r Could be defined as fun ref x gt x value prefix a ref gt a gt unit r a stores the value of a in reference r value incr int ref gt unit Increment the integer contained in the given reference Could be defined as fun r gt r succ r value decr int ref gt unit Decrement the integer contained in the given reference Could be defined as fun r gt r pred r Chapter 13 The core library 131 13 15 stream operations on streams type a stream The type of streams containing values of type a exception Parse_failure Raised by parsers when none of the first component of the stream patterns is accepted exception Parse_error Raised by parsers when the first component of a stream pattern is accepted but one of the following components is rejected value stream_next a stream gt a stream_next s returns the first element of stream s and removes it from the stream Raise Parse_failure if the stream is empty value stream_from unit gt a gt a stream stream_from f returns the stream which fetches its terminals using the function f This function could be defined as let rec stream_from f lt f s
144. ilename is either a compiled interface file zi file or a compiled bytecode file zo file If filename has the format mod zi 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 zi If filename has the format mod zo this means you are trying to link a bytecode object file that does not exist yet Fix compile mod ml 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 file filename The compiler produces this error when it tries to read a compiled interface file zi file that has the wrong structure This means something went wrong when this zi 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 zi file is modified after its creation by the compiler Fix remove the corrupted zi file and rebuild it 50 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 expre
145. iler sections 8 4 1 Header and trailer The header and the trailer sections are Caml Light 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 required by the semantic actions of the rules The trailer goes at the end of the output file 8 4 2 Declarations Declarations are given one per line They all start with a sign Chapter 8 Lexer and parser generators camllex camlyacc 75 token symbol symbol Declare the given symbols as tokens terminal symbols These symbols are added as constant constructors for the token concrete type 4token lt type gt symbol symbol Declare the given symbols as tokens with an attached attribute of the given type These sym bols are added as constructors with arguments of the given type for the token concrete type The type part is an arbitrary Caml Light 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 ml output file but not to the mli output file while the type part of a token declaration is copied to both start symbol symbol Declare the given symbols as entry points for the grammar For each entry point a parsing function with the s
146. iles Either you have forgotten to provide an implementation for the module named mod on the command line typically the file named mod zo or a library containing that file Fix add the missing ml or zo 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 one of the global variables defined in module mod Fix change the order of ml and zo 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 mod1__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 gin the same module e Parameterize one function by the other That is instead of having 52 modi ml let f x mod2__g 3 mod2 ml let gy modi__f 33 define modi ml let f gx ga 33 mod2 ml1 let rec gy modi_fg 3 and link modi before mod2 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 ml let g y modi__f 33 modi__forward_g g Unavailable C primitive f This error appears when trying to link code that
147. in the input stream of the character following the last character of the matched string The first character of the stream has position 0 Chapter 14 The standard library 153 14 9 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 type Ca b t The type of maps from type a to type b value empty a gt a gt int gt Ca b t The empty map The argument is 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 Examples a suitable ordering function for type int is prefix You can also use the generic structural comparison function eq__compare value add a gt b gt a b t gt Ca b t add x y m returns a map containing the same bindings as m plus a binding of x to y Previous bindings for x in m are not removed but simply hidden they reappear after performing a remove operation This is the semantics of association lists value find a gt a b t gt
148. in the values printed by the toplevel loop value remove_printer string gt unit remove_printer printername removes the function named printername from the table of toplevel printers value set_print_depth int gt unit set_print_depth n limits the printing of values to a maximal depth of n The parts of values whose depth exceeds n are printed as ellipsis value set_print_length int gt unit set_print_length n limits the number of value nodes printed to at most n Remaining parts of values are printed as ellipsis value debug_mode bool gt unit Set whether extended module interfaces must be used debug_mode true or not debug_mode false Extended module interfaces are zix files that describe the actual implementation of a module including private types and variables They are generated when compiling with camlc g or with the compile function above when debug_mode is true When debug_mode is true toplevel phrases can refer to private types and variables of modules and private functions can be traced with trace Setting debug_mode true is equivalent to starting the toplevel with the g option value cd string gt unit Change the current working directory value directory string gt unit Add the given directory to the search path for files Same behavior as the I option or the directory directive 58 5 3 The toplevel and the module system Toplevel phrases can refer to identifiers defin
149. int formatter gt int gt unit value pp_print_float formatter gt float gt unit value pp_print_char formatter gt char gt unit value pp_print_bool formatter gt bool gt unit value pp_print_break formatter gt int gt int gt unit value pp_print_cut formatter gt unit gt unit value pp_print_space formatter gt unit gt unit value pp_force_newline formatter gt unit gt unit value pp_print_flush formatter gt unit gt unit value pp_print_newline formatter gt unit gt unit value pp_print_if_newline formatter gt unit gt unit value pp_open_tbox formatter gt unit gt unit value pp_close_tbox formatter gt unit gt unit value pp_print_tbreak formatter gt int gt int gt unit value pp_set_tab formatter gt unit gt unit value pp_print_tab formatter gt unit gt unit value pp_set_margin formatter gt int gt unit value pp_get_margin formatter gt unit gt int value pp_set_max_indent formatter gt int gt unit value pp_get_max_indent formatter gt unit gt int value pp_set_max_boxes formatter gt int gt unit value pp_get_max_boxes formatter gt unit gt int value pp_over_max_boxes formatter gt unit gt bool value pp_set_ellipsis_text formatter gt string gt unit value pp_get_ellipsis_text formatter gt unit gt string value pp_set_formatter_out_channel formatter gt out_channe
150. 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 position 0 as usual value search_forward regexp gt string gt int gt int search_forward r s start searchs 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 value search_backward regexp gt string gt int gt int Same as search_forward but the search proceeds towards the beginning of the string value matched_string string gt string matched_string s returns the substring of s that was matched by the latest string_match search_forward or search_backward The user must make sure that the parameter s is the same string that was passed to the matching or searching function value match_beginning unit gt int value match_end unit gt int match_beginning returns the position of the first character of the substring that was matched by string_match search_forward or search_backward match_end returns the position of the character following the last character of the matched substring value 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
151. ion and can be referred to by the implementation phrases Type definitions that are not abstract type declarations must not be redefined in the module implementation In contrast the type constructors that are declared abstract in a module interface must be defined in the module implementation with the same names Directives modify the behavior of the compiler on the subsequent phrases of the module inter face as described in section 2 9 Directives apply only to the interface currently being compiled in particular they have no effect on other modules that refer to globals exported by the interface being compiled 34 Chapter 3 Language extensions This chapter describes the language features that are implemented in Caml Light but not described in the Caml Light reference manual In contrast with the fairly stable kernel language that is described in the reference manual the extensions presented here are still experimental and may be removed or changed in the future 3 1 Streams parsers and printers Caml Light comprises a built in type for streams possibly infinite sequences of elements that are evaluated on demand and associated stream expressions to build streams and stream patterns to destructure streams Streams and stream patterns provide a natural approach to the writing of recursive descent parsers Streams are presented by the following extensions to the syntactic classes of expressions expr us lt gt
152. ion is automatically added if not present The load function behaves much like include except that a new module is created with name the base name of the source file name Global identifiers defined in the source file are entered in this module instead of the top module as in the case of include For instance assuming file foo ml contains the single phrase let bar 1 executing load foo defines the identifier foo__bar with value 1 Caveat the loaded module is not automatically opened the identifier bar does not automatically complete to foo__bar To achieve this you must execute the directive open foo afterwards value compile string gt unit Compile the source code for a module implementation or interface m1 or m1i file Compilation proceeds as with the batch compiler and produces the same results as camlc c If the toplevel system is in debugging mode option g or function debug_mode below the compilation is also performed in debugging mode as when giving the g option to the batch compiler The result of the compilation is left in files zo zi zix The compiled code is not loaded in memory Use load_object to load a zo file produced by compile value load_object string gt unit Load in memory the compiled bytecode contained in the given file The zo extension is automatically added to the file name if not present The bytecode file has been produced either by the standalone compiler camlc or by the c
153. irectory to the path of directories searched for compiled module interface files This is equivalent to the I command line option to the batch compiler and the toplevel system 42 Part III The Caml Light commands Chapter 4 Batch compilation camlc This chapter describes how Caml Light programs can be compiled non interactively and turned into standalone executable files This is achieved by the command camlc which compiles and links Caml Light source files Mac This command is not a standalone Macintosh application To run camlc you need the Macintosh Programmer s Workshop MPW programming environment The programs generated by camlc are also MPW tools not standalone Macintosh applications 4 1 Overview of the compiler The camlc command has a command line interface similar to the one of most C compilers It accepts several types of arguments source files for module implementations source files for module interfaces and compiled module implementations e Arguments ending in mli are taken to be source files for module interfaces Module interfaces declare exported global identifiers define public data types and so on From the file z m1i the camlc compiler produces a compiled interface in the file x zi e Arguments ending in ml are taken to be source files for module implementation Mod ule implementations bind global identifiers to values define private data types and contain expressions to be evaluated for thei
154. is chapter explains how to install Caml Light on your machine 1 1 The Unix version Requirements Any machine that runs under one of the various flavors of the Unix operating system and that has a flat non segmented 32 bit or 64 bit address space 4M of RAM 2M of free disk space The graphics library requires X11 release 4 or later Installation The Unix version is distributed in source format as a compressed tar file named cl74unix tar gz To extract move to the directory where you want the source files to reside transfer cl74unix tar gz to that directory and execute zcat cl74unix tar gz tar xBf This extracts the source files in the current directory The file INSTALL contains complete instruc tions on how to configure compile and install Caml Light Read it and follow the instructions Troubleshooting See the file INSTALL 1 2 The Macintosh version Requirements Any Macintosh with at least 1M of RAM 2M is recommended running System 6 or 7 About 850K of free space on the disk The parts of the Caml Light system that support batch compilation currently require the Macintosh Programmer s Workshop MPW version 3 2 MPW is Apple s development environment and it is distributed by APDA Apple s Programmers and Developers Association See the file READ ME in the distribution for APDA s address Installation Create the folder where the Caml Light files will reside Double click on the file cl74macbin sea from the di
155. it gt unit print_tab is equivalent to print_tbreak 0 0 Ellipsis value set_ellipsis_text string gt unit Set the text of the ellipsis printed when too many boxes are opened a single dot by default value get_ellipsis_text unit gt string Return the text of the ellipsis Redirecting formatter output value set_formatter_out_channel out_channel gt unit Redirect the pretty printer output to the given channel value 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 to ptn 1 of s The flush function is called whenever the pretty printer is flushed using print_flush or print_newline value get_formatter_output_functions unit gt string gt int gt int gt unit unit gt unit Return the current output functions of the pretty printer Chapter 14 The standard library 145 Multiple formatted output type formatter Abstract data type corresponding to a pretty printer and all its machinery Defining new pretty printers permits the output of material in parallel on several channels Parameters of the pretty printer are local to the pretty printer margin maximum in
156. ix 192 infix 117 120 infix 117 infix 192 infix 117 120 infix 117 infix 192 infix 117 120 infix 117 infix 192 lt Gnfix 115 lt infix 118 lt infix 193 lt lt nfo 115 infix 118 lt infix 193 lt gt infix 115 lt gt infix 118 lt gt infix 193 infix 115 infix 118 infix 193 infix 116 infix 115 x 118 x 193 infix 115 gt infix 118 vv I infi gt infi n i i 207 gt infix 193 infix 127 infix 132 infix 114 abs 121 abs_float 119 abs_num 193 accept 186 access 178 acos 118 add 139 150 153 156 158 add_float 117 add_int 120 add_num 192 alarm 183 approx_num_exp 194 approx_num_fix 194 arg module 137 arith_status 194 arith_status module 194 asin 118 asr infix 121 assoc 129 assq 129 atan 118 atan2 118 background 165 Bad exception 138 baltree module 138 basename 140 big_int_of_num 194 bind 186 black 165 blit_image 168 blit_string 133 208 blit_vect 135 blue 165 bool module 113 bounded_split 199 Break exception 161 builtin module 114 button_down 169 catch_break 161 cd 57 ceil 118 ceiling_num 192 char module 115 char_for_read 115 char_of_int 115 chdir 161 179 check_suffix 140 chmod 178 choose 158 chop_suffix 140 chown 178 clear 150 156
157. k 177 list module 127 list_it 128 list_it2 128 list_length 127 list_of_vect 135 listen 186 lnot 121 load 56 load_object 56 localtime 183 lockf 181 log 118 logi10 118 lor infix 121 lseek 176 lshift_left 121 lshift_right 121 1sl infix 121 lsr infix 121 lstat 177 1t_float 118 1t_int 121 1t_num 193 lt_string 133 lxor infix 121 magenta 165 major 149 make_formatter 145 make_image 167 make_lexer 149 make_matrix 134 make_string 132 make_vect 134 map 128 map module 153 map2 128 map_combine 130 211 map_vect 135 map_vect_list 135 match_beginning 198 match_end 198 Match_failure exception 24 26 114 matched_group 198 matched_string 198 max 116 max_int 121 max_num 193 mem 129 157 mem_assoc 129 memq 129 merge 158 min 116 min_int 121 min_num 193 minor 148 minus 117 120 minus_float 117 minus_int 120 minus_num 192 mkdir 179 mkfifo 180 mod infix 120 mod_float 119 mod_num 192 modf 119 modify 139 mouse_pos 169 moveto 166 mult_float 117 mult_int 120 mult_num 192 nat_of_num 194 neq_float 118 neq_int 120 neq_string 133 new 150 156 159 nice 175 normalize_num 191 not infix 114 Not_found exception 116 nth_char 132 212 num module 191 num_of _big_int 194 num_of_float 194 num_of_int 194 num_of_nat 194 num_of_ratio 194 num_of_string 194 numerator_num 191 open 161 175
158. l gt unit value pp_set_formatter_output_functions formatter gt string gt int gt int gt unit gt unit gt unit gt unit value pp_get_formatter_output_functions formatter gt unit gt string gt int gt int gt unit unit gt unit The basic functions to use with formatters 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 value fprintf formatter gt a formatter unit format gt a fprintf ff format argi 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 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 or hov which stand respectively for an horizontal vertical horizontal vertical and horizontal or vertical box close the
159. l de Rauglaudre in the proceedings of the 1992 ACM conference on Lisp and Functional Programming 3 2 Guards Cases of a pattern matching 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 match expr with pattern whencond gt expr pattern whencond gt expr Same syntax for the fun function and try with constructs During matching if the value of expr 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 Chapter 3 Language extensions 37 3 3 Range patterns In patterns Caml Light recognizes the form c d two character constants separated by as a shorthand for the pattern c c c c C1 c c C2 c wae c Cn c c d c where c1 2 Cn are the characters that occur between c and d in the ASCII character set For instance the pattern 0 9 matches all characters that are digits 3 4 Recursive definitions of values Besides let rec definitions of functional values as described in the reference m
160. le a2 in degrees The current point is unchanged value 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 value 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 value 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 value draw_char char gt unit value draw_string string gt unit Draw a character or a character string with lower left corner at current position After drawing the current position is set to the lower right corner of the text drawn value set_font string gt unit value set_text_size int gt unit Set the font and character size used for drawing text The interpretation of the arguments to set_font and set_text_size is implementation dependent value text_size string gt int int Return the dimensions of the given text if it were drawn with the current font and size Chapter 15 The graphics library 167 Filling value fill_rect int gt int gt int gt int gt unit fill_rect x y w h fills the rectangle with lower left corner a
161. le being compiled as a constant constructor Record types The type definition typeparams ident label decl label decl defines a record type The label declarations label decl label decl describe the labels associated to this record type The label declaration ident typexpr declares the local name ident in the module being compiled as a label whose argument has type typexpr The label declaration mutable ident typexpr behaves similarly in addition it allows physical modification over the argument to this label Chapter 2 The core Caml Light language 31 Type abbreviations The type definition typeparams ident typexpr defines the type constructor ident as an abbrevi ation for the type expression typexpr Abstract types The type definition typeparams ident defines ident as an abstract type When appearing in a mod ule interface this definition allows exporting a type constructor while hiding how it is represented in the module implementation 2 8 2 Exception definitions exception definition exception constr decl and constr decl Exception definitions add new constructors to the built in variant type exn of exception values The constructors are declared as for a definition of a variant type 2 9 Directives directive open string close string ident string Directives control the behavior of the compiler They apply to the remainder of the current compilation unit The two di
162. lue returned by the first call to alloc must be stored in a registered root The value returned by the second call to alloc can reside in the un registered local variable result since we won t do any further allocation in this function In the example 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 ii i2 int il i2 value tail Push_roots r 1 r 0 alloc 2 1 Allocate a cons cell Field r 0O 0 Val_int il car the integer il Field r 0O 1 Val_int 0 A dummy value tail alloc 2 1 Allocate the other cons cell Field tail 0 Val_int i2 car the integer i2 Field tail 1 Atom 0 cdr the empty list modify amp Field r l0 1 tail cdr of the result tail Pop_roots return r 0 It would be incorrect to perform Field r 0 1 tail directly because the allocation of tail has taken place since r 0 was allocated 12 6 A complete example This section outlines how the functions from the Unix curses library can be made available to Caml Light programs First of all here is the interface curses m1i that declares the curses primitives and data types 108 type window The type window remains abstract value and and and and and and and and and 33 Ok initscr unit gt window 1 curses_initscr endwin unit g
163. lues for the arguments and an integer which is the number of arguments provided value prim_with_lots_of_args argv argn value argv int argn argv O The first argument argv 6 The seventh argument Implementing a user primitive is actually two separate tasks on the one hand decoding the arguments to extract C values from the given Caml Light values and encoding the return value as a Caml Light 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 Light values to C values call the first function and convert the returned C value to Caml Light value For instance here is the stub code for the input primitive value input channel buffer offset length value channel buffer offset length return Val_long getblock struct channel channel amp Byte buffer 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 hard work is performed by the function getblock which is declared as long getblock cha
164. m other options str zo other files lstr For interactive use of the str library run camllight camlstr Mac This library is not available PC This library is not available 18 1 str regular expressions and high level string processing Regular expressions type regexp The type of compiled regular expressions value regexp string gt regexp Compile a regular expression The syntax for regular expressions is the same as in Gnu Emacs The special characters are The following constructs are recognized matches any character except newline postfix matches the previous expression zero one or several times postfix matches the previous expression one or several times postfix matches the previous expression once or not at all L character set ranges are denoted with as in a z an initial as in 0 9 complements the set 197 198 matches at beginning of line matches at end of line l infix alternative between two expressions C grouping and naming of the enclosed expression 1 the text matched by the first expression 2 for the second expression etc b matches word boundaries quotes special characters value 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 String matching and searching value string_match regexp gt string gt
165. n TCSANOW TCSADRAIN TCSAFLUSH value 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 value 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 value tcdrain file_descr gt unit Waits until all output written on the given file descriptor has been transmitted type flush_queue TCIFLUSH TCOFLUSH TCIOFLUSH value 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 value 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 TCO
166. n ident above are then evaluated following the rules in section 2 7 1 In the initial environment they evaluate to built in functions whose behavior is described in the table The behavior of the constructions prefix op expr and expr infix op expr may change if the meaning of the identifiers associated to prefix op or infix op is changed either by redefinition of the identifiers or by modification of the list of opened modules through the open and close directives Chapter 2 The core Caml Light language 29 Operator Associated Behavior in the default environment identifier prefix Integer addition prefix Integer subtraction minus Integer negation prefix Integer multiplication prefix Integer division Raise Division_by_zero if second argu ment is zero The result is unspecified if either argument is negative prefix mod Integer modulus Raise Division_by_zero if second argu ment is zero The result is unspecified if either argument is negative prefix Floating point addition prefix Floating point subtraction minus_float Floating point negation prefix Floating point multiplication prefix Floating point division Raise Division_by_zero if second argument is zero prefix Floating point exponentiation prefix List concatenation prefix String concatenation prefix Dereferencing return the current contents of a reference prefix Reference assignment update the reference given as first
167. n 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 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 2 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 neconstr expr evaluates to the variant value whose constructor is ncconstr and whose argument is the value of expr For lists some syntactic sugar is provided The expression expr expr stands for the constructor prefix 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 expr The expression expr expr is equivalent to expr expr and therefore evaluates to the list whose elements are the values of expr to expr Records The expr
168. n of the upper left corner of the graphics window If omitted width height default to 600 400 and 2 y default to 10 10 15 1 graphics machine independent graphics primitives exception Graphic_failure of string Raised by the functions below when they encounter an error Initializations value open_graph string gt unit Show the graphics window or switch the screen to graphic mode The graphics window is cleared 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 value close_graph unit gt unit Delete the graphics window or switch the screen back to text mode Chapter 15 The graphics library 165 value clear_graph unit gt unit Erase the graphics window value size_x unit gt int value size_y unit gt int Return the size of the graphics window Coordinates of the screen pixels range over O size_x 1and0 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 range 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 v
169. nes into one single library this will not result in bigger executables The usage for camllibr is camllibr options file zo file zo where file zo through file zo are the object files to pack together The order in which these file names are presented on the command line is relevant the compiled phrases contained in the library will be executed in that order Remember that it is a link time error to refer to a global variable that has not yet been defined 67 68 7 2 Options The following command line options are recognized by camllibr I directory Add the given directory to the list of directories searched for the input zo files By default the current directory is searched first then the standard library directory Directories added with I are searched after the current directory but before the standard library directory When several directories are added with several I options on the command line these direc tories are searched from right to left the rightmost directory is searched first the leftmost is searched last o library name Specify the name of the output file The default is Library zo PC The following option is also supported response file Process the files whose names are listed in file response file just as if these names appeared on the command line File names in response file are separated by blanks spaces tabs newlines This option allows to overcome silly limitations on the le
170. ng Return the next entry in a directory Raise End_of_file when the end of the directory has been reached value rewinddir dir_handle gt unit Reposition the descriptor to the beginning of the directory value closedir dir_handle gt unit Close a directory descriptor Pipes and redirections value pipe unit gt file_descr file_descr 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 entrace to the pipe value dup file_descr gt file_descr Duplicate a descriptor value dup2 file_descr gt file_descr gt unit dup2 fdi fd2 duplicates fd1 to fd2 closing fd2 if already opened 180 value open_process_in string gt in_channel value open_process_out string gt out_channel value open_process string gt in_channel out_channel High level pipe and process management These functions run the given command in parallel with the program and return channels connected to the standard input and or the standard output of the command The command is interpreted by the shell bin sh cf system Warning writes on channels are buffered hence be careful to call flush at the right times to ensure correct synchronization value close_process_in in_channel gt process_status value close_process_out out_channel gt process_status value close_process in_channel out_channel gt process_status Close c
171. ngth of the command line 7 3 Turning code into a library To develop a library it is usually more convenient to split it into several modules that reflect the internal structure of the library From the standpoint of the library users however it is preferable to view the library as a single module with only one interface file zi file and one implementation file zo file linking is easier and there is no need to put a bunch of open directives nor to have to remember the internal structure of the library The camllibr command allows having a single zo file for the whole library Here is how the Caml Light module system can be used some say abused to have a single zi file for the whole library To be more concrete assume that the library comprises three modules windows images and buttons The idea is to add a fourth module mylib that re exports the public parts of windows images and buttons The interface mylib m1li contains definitions for those types that are public exported with their definitions declarations for those types that are abstract exported without their definitions and declarations for the functions that can be called from the user s code File mylib mli type a option None Some of a a public type type window and image and button three abstract types value new_window int gt int gt window the public functions and draw_image image gt window gt int
172. nish de for German See the file camlmsgs txt in the Caml Light standard library directory for a list of available languages When an unknown language is specified or no translation is available for a message American English is used by default o exec file Specify the name of the output file produced by the linker Unix The default output name is a out in keeping with the tradition PC The default output name is caml_out exe Mac The default output name is Caml Out 48 0 module set Specify which set of standard modules is to be implicitly opened at the beginning of a compilation There are three module sets currently available cautious provides the standard operations on integers floating point numbers characters strings arrays as well as exception handling basic input output etc Operations from the cautious set perform range and bound checking on string and array operations as well as various sanity checks on their arguments fast provides the same operations as the cautious set but without sanity checks on their arguments Programs compiled with 0 fast are therefore slightly faster but unsafe none suppresses all automatic opening of modules Compilation starts in an almost empty environment This option is not of general use except to compile the standard library itself The default compilation mode is 0 cautious See chapter 13 for a complete listing of the modules in the cautious and fast
173. nly if needed Actually e1 amp e2 is equivalent to if e1 then e2 else false and el or e2 is equivalent to if e1 then true else e2 value prefix not bool gt bool The boolean negation value string_of_bool bool gt string Return a string representing the given boolean 13 2 builtin base types and constructors This module defines some types and exceptions for which the language provides special syntax and are therefore treated specially by the compiler type int type float type string type char The types of integers floating point numbers character strings and characters respectively type exn The type of exception values type bool false true The type of boolean values type a vect The type of arrays whose elements have type a type unit The type of the unit value type a list prefix of a a list The type of lists type a option None Some of a The type of optional values exception Match_failure of string int int The exception raised when a pattern matching fails The argument indicates the position in the source code of the pattern matching source file name position of the first character of the matching position of the last character Chapter 13 The core library 115 13 3 char character operations value int_of_char char gt int Return the ASCII code of the argument value char_of_int int gt char Return the character with the given ASCII code
174. nnel p n struct channel channel char p long n To write C code that operates on Caml Light values the following include files are provided Chapter 12 Interfacing C with Caml Light 101 dude file mlvalues h definition of the value type and conversion macros alloc h allocation functions to create structured Caml Light objects memory h miscellaneous memory related functions for in place modification of structures etc These files reside in the Caml Light standard library directory usually usr local lib caml light 12 1 3 Linking C code with Caml Light code The Caml Light runtime system comprises three main parts the bytecode interpreter the mem ory manager and a 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 Light 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 In the custom runtime mode the Caml Light linker scans the bytecode object files zo 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 byte
175. nts lines according to the box structure Rule of thumb for casual users use simple boxes as obtained by open_box 0 use simple break hints as obtained by print_cut that outputs a simple break hint or by print_space that ouputs a space indicating a break hint once a box is opened display its material with basic printing functions e g print_int and print_string when the material for a box has been printed call close_box to close the box at the end of your routine evaluate print_newline to close all remaining boxes and flush the pretty printer Chapter 14 The standard library 141 You may alternatively consider this module as providing an extension to the printf facility you can simply add pretty printing annotations to your regular printf formats as explained below in the documentation of the function fprintf 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 value open_box int gt unit open_box d opens a new pret
176. oaded in memory just as if you had typed load_object foo load_object bar load_object gee 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 5 The toplevel system camllight 61 5 6 Options The following command line options are recognized by camlmktop ccopt option Pass the given option to the C compiler and linker when linking in custom runtime mode See the corresponding option for camlc in chapter 4 custom Link in custom runtime mode See the corresponding option for camlc in chapter 4 g Add debugging information to the toplevel file produced which can then be debugged with camldebug chapter 9 I directory Add the given directory to the list of directories searched for compiled object code files zo o exec file Specify the name of the toplevel file produced by the linker Unix The default is camltop out PC The default is camltop exe The name must have exe extension 62 Chapter 6 The runtime system camlrun The camlrun command executes bytecode files produced by the linking phase of the camlc com mand Mac This command is a MPW tool not a standalone Macintosh application 6 1 Overview The camlrun command comprises three main parts the bytecode interpreter that actually executes bytecode files the memory allocator and garbage collector
177. ocess The returned integer is 0 for the child process the pid of the child process for the parent process value wait unit gt int process_status Wait until one of the children processes die and return its pid and termination status value waitopt wait_flag list gt int process_status Same as wait but takes a list of options to avoid blocking or also report stopped children The pid returned is 0 if no child has changed status value waitpid wait_flag list gt int gt int process_status Same as waitopt but waits for the process whose pid is given Negative pid arguments represent process groups Chapter 16 The unix library Unix system calls 175 value 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 value getpid unit gt int Return the pid of the process value getppid unit gt int Return the pid of the parent process value 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 Basic file input output type file_descr The abstract type of file descriptors value stdin file_descr value stdout file_
178. odule system of Standard ML e Jeffrey D Ullman Elements of ML programming Prentice Hall 1993 Another good introduction to programming in Standard ML No realistic examples but a very detailed presentation of the language constructs e Ryan Stansifer ML primer Prentice Hall 1992 A short but nice introduction to programming in Standard ML e Th r se Accart Hardin and V ronique Donzeau Gouge Vigui Concepts et outils de la pro grammation Du fonctionnel Vimp ratif avec Caml et Ada InterEditions 1992 203 204 A first course in programming that first introduces the main programming notions in Caml then shows them underlying Ada Intended for beginners slow paced for the others e Rachel Harrison Abstract Data Types in Standard ML John Wiley amp Sons 1993 A presentation of Standard ML from the standpoint of abstract data types Uses intensively the Standard ML module system e Harold Abelson and Gerald Jay Sussman Structure and Interpretation of Computer Pro grams The MIT press 1985 French translation Structure et interpr tation des programmes informatiques InterEditions 1989 An outstanding course on programming taught in Scheme the modern dialect of Lisp Well worth reading even if you are more interested in ML than in Lisp 19 2 Descriptions of ML dialects The books and reports below are descriptions of various programming languages from the ML family They assume some familiarity with
179. of all identifiers defined in the standard library and an index of Caml Light keywords Conventions The Caml Light system comes in several versions for Unix machines for Macintoshes and for PCs The parts of this manual that are specific to one version are presented as shown below Unix This is material specific to the Unix version Mac This is material specific to the Macintosh version PC This is material specific to the PC version License The Caml Light system is copyright 1989 1990 1991 1992 1993 1994 1995 1996 1997 Institut National de Recherche en Informatique et en Automatique INRIA INRIA holds all ownership rights to the Caml Light system See the file COPYRIGHT in the distribution for the copyright notice The Caml Light system can be freely redistributed More precisely INRIA grants any user of the Caml Light system the right to reproduce it provided that the copies are distributed under the conditions given in the COPYRIGHT file The present documentation is distributed under the same conditions 6 Foreword Availability by FTP The complete Caml Light distribution resides on the machine ftp inria fr The distribution files can be transferred by anonymous FTP Host ftp inria fr Internet address 192 93 2 54 Login name anonymous Password your e mail address Directory lang caml light Files see the index in file README Part I Getting started Chapter 1 Installation instructions Th
180. of the compiled module by taking the 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 The produced zi and zo files have the same base name as the source file hence the compiled files produced by the compiler always have their base name equal to the name of the module they describe for zi files or implement for zo files For compiled interface files zi files this invariant must be preserved at all times since the compiler relies on it to load the compiled interface file for the modules that are used from the module being compiled Hence it is risky and generally incorrect to rename zi files 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 Compiled bytecode files zo files on the other hand can be freely renamed once created That s because 1 zo files contain the true name of the module they define so there is no need to derive that name from the file name 2 the linker never attempts to find by itself the zo file that implements a module of a given name it relies on the user providing the list of zo files by hand 4 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 f
181. 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 Light strings can contain embedded null characters that will confuse the usual C functions over strings e Double_val v returns the floating point number contained in value v with type double The expressions Field v n Code_val v Env_val v Byte v n Byte_u v n and Double_val v 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 12 4 4 Allocating blocks 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 blocks with size greater than to Max_young_wosize The constant Max_young_wosize is declared in the 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 e 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
182. ogram 9 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 gt are located in the source code e Following a function application arg e After receiving an argument to a function fun xe y Z gt If a curried function is defined by pattern matching with several cases events corresponding to the passing of arguments are displayed on the first case of the function because pattern matching has not yet determined which case to select fun patira pat2p lt pat3 gt pa 82 e On each case of a pattern matching definition function match with construct try with construct function pati gt ed expri J patN gt exprN e Between subexpressions of a sequence expri mh expr2 pd bo exprN e In the two branches of a conditional expression if cond then em expri els
183. ompile function Global identifiers defined in the file being loaded are entered in their own module not in the top module just as with the load function value trace string gt unit After the execution of trace foo all calls to the global function named foo will be traced That is the argument and the result are displayed for each call as well as the exceptions escaping out of foo either raised by foo itself or raised by one of the functions called from foo If foo is a curried function each argument is printed as it is passed to the function Only functions implemented in ML can be traced system primitives such as string_length or user supplied C functions cannot Chapter 5 The toplevel system camllight 57 value untrace string gt unit Executing untrace foo stops all tracing over the global function named foo value verbose_mode bool gt unit verbose_mode true causes the compile function to print the inferred types and other information verbose_mode false reverts to the default silent behavior value install_printer string gt unit install_printer printername registers the function named printername as a printer for objects whose types match its argument type That is the toplevel loop will call printername when it has such an object to print The printing function printername must use the format library module to produce its output otherwise the output of printername will not be correctly located
184. on F s the annotation will be sn An additional argument specifies the output file For instance camlpro f test camlpro dump foo ml foo_profiled ml will save the annotated program in file foo_profiled ml Otherwise the annotated program is written on the standard output 10 4 Known bugs The following situation file x m1 Chapter 10 Profiling camlpro 93 let a 1 X__a 33 will break the profiler More precisely one should avoid to refer to symbols of the current module with the qualified symbol syntax 94 Chapter 11 Using Caml Light under Emacs This chapter describes how Caml Light can be used in conjunction with Gnu Emacs version 19 version 18 is also partially supported Unix The Emacs Lisp files implementing the Caml Emacs interface are in contrib camlmode in the distribution Mac The Caml Emacs interface is not available PC The Caml Emacs interface is not available 11 1 Updating your emacs The following initializations must be added to your emacs file setq auto mode alist cons mlLiylp caml mode auto mode alist autoload caml mode caml Major mode for editing Caml code t C autoload run caml inf caml Run an inferior Caml process t autoload camldebug camldebug Run the Caml debugger t 11 2 The caml editing mode The caml mode function is a major editing mode for Caml source files It provides the correct syntax tables comment syntax
185. onassoc The symbols are usually tokens They can also be dummy nonterminals for use with the 4prec directive inside the rules 76 8 4 3 Rules The syntax for rules is as usual nonterminal symbol symbol semantic action 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 Light expressions that are evaluated to produce the se mantic 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 Actions occurring in the middle of rules are not supported Error recovery is not implemented 8 5 Options The camlyacc 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 s Generate a grammar ml1 file with smaller phrases Semantic actions are presented in the grammar ml output file as one large vector of functions By default this vector is built by a single phrase When the grammar is large or contains complicated semantic actions t
186. oose whichever approach is more adapted to your parsing problem Mac These commands are MPW tool not standalone Macintosh applications 8 1 Overview of camllex The camllex 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 lexer m11 executing camllex lerer mll produces Caml Light code for a lexical analyzer in file lexer ml This file defines one lexing func tion 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 create_lexer_channel create_lexer_string and create_lexer from module 71 72 lexing create lexer buffers that read from an input channel a character string or any reading function respectively See the description of module lexing in chapter 13 When used in conjunction with a parser generated by camlyacc the semantic actions compute a value belonging to the type token defined by the generated parsing module See the description of camlyacc below 8 2 Syntax of lexer definitions The format of lexer definitions is as follows header rule enitrypoint parse regexp action J regexp action and entrypoint parse and
187. own bugs 2 ee 11 Using Caml Light under Emacs 11 1 Updating your emacs aoaaa ee 11 2 The caml editing mode 0 00002 02 eee ee ee ee 11 3 Running the toplevel as an inferior process 2 2 ee 11 4 Running the debugger as an inferior process 02 0000004 12 Interfacing C with Caml Light 12 1 Overview and compilation information 0 0 00 0 20220048 12 2 The value type 2 a 12 3 Representation of Caml Light data types 0 0 2 0220200 12 4 Operations on values aoaaa ee ee 12 5 Living in harmony with the garbage collector 0 2 2000 4 12 6 A complete example 2 2 0 0 a IV The Caml Light library 13 The core library 13 1 bool boolean operations 2 2 a 13 2 builtin base types and constructors 2 2 0 ee ee 13 3 char character operations oaoa a ee 13 4 eq generic comparisons 2 ee 13 5 exc exceptions 2 ee 13 6 fchar character operations without sanity checks 13 7 float operations on floating point numbers 2 02 208 13 8 fstring string operations without sanity checks 0 4 13 9 fvect operations on vectors without sanity checks 13 10 int operations on integers 2 2 ee ee 13 11 io buffered input and output 2 2 ee ee 13 12 list operations on lists 2 aoaaa ee 13 13 pair operations on pairs 2 ee 13 14 ref operations on references 2 2 2
188. passwd with the given user id or raise Not_found value getgrgid int gt group_entry Find an entry in group with the given group id or raise Not_found Internet addresses type inet_addr The abstract type of Internet addresses value inet_addr_of_string string gt inet_addr value string_of_inet_addr inet_addr gt string Conversions between string with the format XXX YYY ZZZ TTT and Internet addresses inet_addr_of_string raises Failure when given a string that does not match this format Sockets type socket_domain PF_UNIX Unix domain PF_INET Internet domain The type of socket domains type socket_type SOCK_STREAM Stream socket SOCK_DGRAM Datagram socket SOCK_RAW Raw socket SOCK_SEQPACKET Sequenced 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 186 type shutdown_command SHUTDOWN _RECEIVE Close for receiving SHUTDOWN_SEND Close for sending SHUTDOWN_ALL Close both The type of commands for shutdown type msg_flag MSG_00B MSG_DONTROUTE MSG_PEEK The flags for
189. perations without sanity checks This module implements the same functions as the string module but does not perform bound checks on the arguments of the functions The functions are therefore faster than those in the string module but calling these functions with incorrect parameters that is parameters that would cause the Invalid_argument exception to be raised by the corresponding functions in the string module can crash the program 13 9 fvect operations on vectors without sanity checks This module implements the same functions as the vect module but does not perform bound checks on the arguments of the functions The functions are therefore faster than those in the vect module but calling these functions with incorrect parameters that is parameters that would cause the Invalid_argument exception to be raised by the corresponding functions in the vect module can crash the program 120 13 10 int operations on integers Integers are 31 bits wide or 63 bits on 64 bit processors All operations are taken modulo 231 or 26 They do not fail on overflow exception Division_by_zero value minus int gt int value minus_int int gt int Unary negation You can write e instead of minus e value succ int gt int succ xis xt1 value pred int gt int pred x is x 1 value prefix int gt int gt int value add_int int gt int gt int Addition value prefix int gt int gt int value sub
190. plevel starts references to foo__x will cause the error foo__x is referenced before being defined In contrast with case 3 above the typechecker has succeeded in finding the compiled interface for module foo But execution cannot proceed because no definition for foo__x has been entered in memory To do so execute load_object foo This loads the file foo zo in memory therefore defining foo__x Then references to foo__x evaluate correctly As in case 3 above references to x still fail because load_object does not open the module it loads Again you will have to do open foo explicitly for x to complete automatically into foo__x 5 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 If filename has the format mod zi this means the current phrase references identifiers from module mod but you have not yet compiled an interface for module mod Fix either load the file mod m1 which will also create in memory the compiled interface for module mod or use camlc to compile mod mli or mod ml creating the compiled interface mod zi before you start the toplevel 60 If filename has the format mod zo this means you are trying to load with load_object a bytecode object file that does not exist yet Fix compile mod ml with camlc before you st
191. pping 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 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 14 8 lexing the run time library for lexers generated by camllex Lexer buffers type lexbuf refill_buff lexbuf gt unit lex_buffer string mutable lex_abs_pos int mutable lex_start_pos int mutable lex_curr_pos int mutable lex_last_pos int mutable lex_last_action lexbuf gt obj 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 152 value create_lexer_channel in_channel gt lexbuf Create a lexer buffer on the given input channel create_lexer_channel inchan returns a lexer buffer which reads from the input channel inchan at the current reading position value create_lexer_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 en
192. pression evaluates to a functional value with m curried arguments When this function is applied to m values v Um the values are matched against each pattern row pattern pattern for 7 from 1 to n If one of these matchings succeeds that is if the value v matches the pattern pattern for all 7 1 m then the expression expr associated to the selected pattern row 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 pattern rows match the arguments the one that occurs first in the function definition is selected If none of the pattern rows matches the argument the exception Match_failure is raised If the function above is applied to less than m arguments a functional value is returned that represents the partial application of the function to the arguments provided This partial application is a function that when applied to the remaining arguments matches all arguments against the pattern rows as described above Matching does not start until all m arguments have been provided to the function hence partial applications of the function to less than m arguments never raise Match_failure All pattern rows in the function body must contain the same number of patterns A variable must not be bound more than once in one pattern row Functions with only one argument can be defined with the fun
193. primer Technical report 92 15 Ecole Normale Sup rieure 1992 Available by anonymous FTP on ftp ens fr Describes a Caml Light library that produces Postscript pictures through high level drawing functions Xavier Leroy Programmation du syst me Unix en Caml Light Technical report 147 INRIA 1992 Available by anonymous FTP on ftp inria fr A Unix systems programming course demonstrating the use of the Caml Light library that gives access to Unix system calls John H Reppy Concurrent programming with events The concurrent ME manual Cornell University 1990 Available by anonymous FTP on research att com Concurrent ML extends Standard ML of New Jersey with concurrent processes that commu nicate through channels and events Jeannette M Wing Manuel Faehndrich J Gregory Morrisett and Scottt Nettles Extensions to Standard ML to support transactions Technical report CMU CS 92 132 Carnegie Mellon University 1992 Available by anonymous FTP on reports adm cs cmu edu How to integrate the basic database operations to Standard ML Emden R Gansner and John H Reppy eXene Bell Labs 1991 Available by anonymous FTP on research att com An interface between Standard ML of New Jersey and the X Windows windowing system Index to the library infix 130 infix 116 amp infix 114 amp amp infix 114 infix 117 120 infix 118 infix 118 infix 192 infix 117 inf
194. r remove modules from that list The modules added with open are checked after the module currently being compiled but before the initial standard library modules variable global name prefix operator name operator name mod fss lt lss t lt lt gt lt lt lt gt lt cconstr x global name C O ncconstr x global name prefix typeconstr global name label global name Depending on the context global names can stand for global variables variable constant value constructors cconstr non constant value constructors neconst type constructors typeconstr or record labels label For variables and value constructors special names built with prefix and an operator name are recognized The tokens and are also recognized as built in constant constructors the empty list and the unit value The syntax of the language restricts labels and type constructors to appear in certain positions where no other kind of global names are accepted Hence labels and type constructors have their own name spaces Value constructors and value variables live in the same name space a global name in value position is interpreted as a value constructor if it appears in the scope of a type declaration defining that constructor otherwise the global name is taken to be a value variable For value constructors the type declaration determines whether a constructor is constant or no
195. r side effects From the file z ml the camlc compiler produces compiled object code in the file x zo If the interface file x mli exists the module implementation z ml is checked against the corresponding compiled interface x zi which is assumed to exist If no interface x mli is provided the compilation of x ml produces a compiled interface file x zi in addition to the compiled object code file x zo The file x zi produced corresponds to an interface that exports everything that is defined in the imple mentation x ml e Arguments ending in zo are taken to be compiled object code These files are linked together along with the object code files obtained by compiling ml arguments if any and the Caml Light standard library to produce a standalone executable program The order in which zo and ml arguments are presented on the command line is relevant global identifiers are initialized in that order at run time and it is a link time error to use a global identifier before 45 46 having initialized it Hence a given x zo file must come before all zo files that refer to identifiers defined in the file x zo The output of the linking phase is a file containing compiled code that can be executed by the Caml Light runtime system the command named camlrun If caml out is the name of the file produced by the linking phase the command camlrun caml out arg argo arg executes the compiled code contained in caml out passing it as ar
196. r the children processes The execution times CPU times of a process Chapter 16 The unix library Unix system calls 183 type tm tm_sec int Seconds 0 59 tm_min int Minutes 0 59 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 Daylight time savings in effect The type representing wallclock time and calendar date value time unit gt int Return the current time since 00 00 00 GMT Jan 1 1970 in seconds value gettimeofday unit gt float Same as time but with resolution better than 1 second value gmtime int gt tm Convert a time in seconds as returned by time into a date and a time Assumes Greenwich meridian time zone value localtime int gt tm Convert a time in seconds as returned by time into a date and a time Assumes the local time zone value alarm int gt int Schedule a SIGALRM signals after the given number of seconds value sleep int gt unit Stop execution for the given number of seconds value times unit gt process_times Return the execution times of the process value utimes string gt int gt int gt unit Set the last access time second arg and last modification time third arg for a file Times are expressed in seconds from 00 00 0
197. racter from the given input channel Raise End_of_file if there are no more characters to read value 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 value input in_channel gt string gt int gt int gt int input chan buff ofs len attempts to read len characters from channel chan storing them in string buff starting at character number ofs 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 no more characters were available at that time input must be called again to read the remaining characters if desired Exception Invalid_argument input is raised if ofs and len do not designate a valid substring of buff value really_input in_channel gt string gt int gt int gt unit really_input chan buff ofs len reads len characters from channel chan storing them in string buff starting at character number ofs Raise End_of_file if the end of file is reached before len characters have been read Raise Invalid_argument really_input if ofs and len do not designate a valid substring of buff Chapter 13 The core library 127 value input_byte in_ch
198. ram execution and highlights the location of the event This display is updated synchronously with the debugger action The following bindings for the most common debugger commands are available in the camldebug progname buffer see section 9 3 for a full explanation of the commands M r run command execute the program forward M s step command execute the program one step forward M b back command execute the program one step backward M 1 last command go back one step in the command history C c gt down command select the stack frame below the current frame C c lt up command select the stack frame above the current frame C c C f finish command run till the current function returns In a buffer in Caml editing mode C x SPC sets a breakpoint at the current position of the point 98 Chapter 12 Interfacing C with Caml Light This chapter describes how user defined primitives written in C can be added to the Caml Light runtime system and called from Caml Light code 12 1 Overview and compilation information 12 1 1 Declaring primitives User primitives are declared in a module interface a mli file in the same way as a regular ML value except that the declaration is followed by the sign the function arity number of arguments and the name of the corresponding C function For instance here is how the input primitive is declared in the interface for the standard library module io value input in_ch
199. rator_num num gt num value denominator_num num gt num 191 192 Arithmetic operations value prefix num gt num gt num value add_num num gt num gt num Addition value minus_num num gt num Unary negation value prefix num gt num gt num value sub_num num gt num gt num Subtraction value prefix num gt num gt num value mult_num num gt num gt num Multiplication value square_num num gt num Squaring value prefix num gt num gt num value div_num num gt num gt num Division value quo_num num gt num gt num value mod_num num gt num gt num Euclidean division quotient and remainder value prefix num gt num gt num value power_num num gt num gt num Exponentiation value is_integer_num num gt bool Test if a number is an integer value integer_num num gt num value floor_num num gt num value round_num num gt num value ceiling_num num gt num Approximate a number by an integer floor_num n returns the largest integer smaller or equal to n ceiling_num n returns the smallest integer bigger or equal to n integer_num n returns the integer closest to n In case of ties rounds towards zero round_num n returns the integer closest to n In case of ties rounds off zero Chapter 17 The num library arbitrary precision rational arithmetic 193 value sign_num num gt int Return 1
200. rd library directory When several directories are added with several I options on the command line these directories are searched from right to left the rightmost directory is searched first the leftmost is searched last Directories can also be added to the search path once the toplevel is running with the directory directive see chapter 3 lang language code Translate the toplevel messages to the specified language The language code is fr for French es for Spanish de for German See the file camlmsgs txt in the Caml Light standard library directory for a list of available languages When an unknown language is specified or no translation is available for a message American English is used by default 0 module set Specify which set of standard modules is to be implicitly opened when the toplevel starts There are three module sets currently available cautious provides the standard operations on integers floating point numbers characters strings arrays as well as exception handling basic input output Operations from the cautious set perform range and bound checking on string and vector operations as well as various sanity checks on their arguments fast provides the same operations as the cautious set but without sanity checks on their arguments Programs compiled with 0 fast are therefore slightly faster but unsafe none suppresses all automatic opening of modules Compilation starts in an almost
201. rectives open and close modify the list of opened modules that the compiler uses to complete unqualified identifiers as described in section 2 2 The directive open string adds the module whose name is given by the string constant string to the list of opened modules in first position The directive close string removes the first occurrence of the module whose name is given by the string constant string from the list of opened modules Implementations can provide other directives provided they follow the syntax ident string where ident is the name of the directive and the string constant string is the argument to the directive The behavior of these additional directives is implementation dependent 2 10 Module implementations implementation impl phrase impl phrase expr value definition exception definition type definition directive value definition let rec let binding and let binding 32 A module implementation consists in a sequence of implementation phrases terminated by double semicolons An implementation phrase is either an expression a value definition a type or exception definition or a directive At run time implementation phrases are evaluated sequentially in the order in which they appear in the module implementation Implementation phrases consisting in an expression are evaluated for their side effects Value definitions bind global value variables in the same way as a let in
202. recv recvfrom send and sendto value 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 value socketpair socket_domain gt socket_type gt int gt file_descr file_descr Create a pair of unnamed sockets connected together value 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 value bind file_descr gt sockaddr gt unit Bind a socket to an address value connect file_descr gt sockaddr gt unit Connect a socket to an address value listen file_descr gt int gt unit Set up a socket for receiving connection requests The integer argument is the maximal number of pending requests value 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 value getsockname file_descr gt sockaddr Return the address of the given socket Chapter 16 The unix library Unix system calls 187 value getpeername file_d
203. rite x to mean any infix symbol starting with 40 Construction or operator Associativity E function application constructor application prefix comparisons lt etc all other infix symbols not amp let match fun function try Some infix and prefix symbols are predefined in the default environment see chapters 2 and 13 for a description of their behavior The others are initially unbound and must be bound before use with a let prefix infix symbol expr or let prefix prefix symbol expr binding 3 10 Directives In addition to the standard open and close directives Caml Light provides three additional directives infix id Change the lexical status of the identifier id in the remainder of the compilation unit id is recognized as an infix operator just like The notation prefix id can be used to refer to the identifier id itself Expressions of the form expr id expr are parsed as the application prefix id expr expr The argument to the infix directive must be an identifier that is a sequence of letters digits and underscores starting with a letter otherwise the infix declaration has no effect Example infix union let prefix union fun x y gt 3 1 2 union 3 4 uninfix id Remove the infix status attached to the identifier id by a previous infix id directive Chapter 3 Language extensions 41 directory dir name Add the named d
204. roots must be called before the C block containing Push_roots r n is exited Roots are automatically un registered if a Caml exception is raised Rule 3 Direct assignment to a field of a block as in Field v n w is safe only if v is a block newly allocated by alloc or alloc_tuple 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 amp Field 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 Chapter 12 Interfacing C with Caml Light 107 value alloc_list_int ii i2 int il i2 value result Push_roots r 1 r 0 alloc 2 1 Allocate a cons cell Field r 0 0 Val_int i2 car the integer i2 Field r 0 1 Atom 0 cdr the empty list result alloc 2 1 Allocate the other cons cell Field result 0 Val_int i1 car the integer il Field result 1 r 0 cdr the first cons cell Pop_roots return result The cons cell allocated first needs to survive the allocation of the other cons cell hence the va
205. ructor argument Example Constructed term Representation Size 0 tag 0 Size 0 tag 0 Size 0 tag 1 Size 0 tag 0 Size 2 tag 1 first field h second field t 12 4 Operations on values 12 4 1 Kind tests e Is_int 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 12 4 2 Operations on integers e Val_long returns the value encoding the long int e Long_val v returns the long int encoded in value v 104 e Val_int 7 returns the value encoding the int i e Int_val v returns the int encoded in value v 12 4 3 Accessing blocks e Wosize_val v returns the size of value v in words excluding the header Tag_val v returns the tag of value v e 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 e Code_val v returns the code part of the closure v e Env_val v returns the environment part of the closure v e string_length v returns the length number of characters of the string v Byte v n returns the nt character of the string v with type char Characters are numbered from 0 to string_length v 1 e 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 e String_val v returns a pointer to the first byte
206. s called once for each matching substring and receives s the whole text as argument value substitute_first regexp gt string gt string gt string gt string Same as global_substitute except that only the first substring matching the regular expression is replaced Splitting value 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 value bounded_split regexp gt string gt int gt string list Same as split but splits into at most n substrings where n is the extra integer parameter 200 Joining value concat string list gt string Same as string__concat catenate a list of string value join string gt string list gt string Catenate a list of string The first argument is a separator which is inserted between the strings Extracting substrings value 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 value 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 value first_chars string gt int gt string first_chars s n returns the first n characters of s This
207. s returned by the stat calls Return the information for the named file string gt stats string gt stats 177 Regular file Directory Character device Block device Symbolic link Named pipe Socket Device number Inode number Kind of the file Access rights Number of links User id of the owner Group id of the owner Device minor number Size in bytes Last access time Last modification time Last status change time Same as stat but in case the file is a symbolic link return the information for the link itself file_descr gt stats Return the information for the file associated with the given descriptor Removes the named file string gt unit string gt string gt unit rename old new changes the name of a file from old to new string gt string gt unit link source dest creates a hard link named dest to the file named new 178 File permissions and ownership type access_permission R_OK Read permission P W_OK Write permission X_OK Execution permission F_OK File exists Flags for the access call value chmod string gt file_perm gt unit Change the permissions of the named file value fchmod file_descr gt file_perm gt unit Change the permissions of an opened file value chown string gt int g
208. sition 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 indentation It is equivalent to print_break 0 0 value print_break int gt int gt unit Insert 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 one 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 value print_flush unit gt unit Flush the pretty printer all opened boxes are closed and all pending text is displayed value print_newline unit gt unit Equivalent to print_flush followed by a new line value force_newline unit gt unit Force a newline in the current box Not the normal way of pretty printing you should prefer break hints value print_if_newline unit gt unit Execute the next formatting command if the preceding line has just been split Otherwise ignore the next formatting command Margin value 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 or bigger than 999999999 value get_margin unit gt int Return th
209. ssion 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 tz are not compatible then the error above is produced In some cases it is hard to understand why the two types t and tz 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 true 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 0 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 Incompatible types with the same names can also appear when a module is changed and recompiled but some of its clients are not recompiled That s because type constructors in zi files are not represented by their name that would not suffice to identify them because of type redefinitions but by unique stamps that are assigned when the type declaration is compiled Consider the three modules modi ml type t A B let f function A gt 0 B gt 1 mod2 ml let g x 1 modi__f x mod3 ml mod2__g modi__A Now assume mod1 ml1 is changed and recompiled but mod2 m1 is not recompiled The recom pilation of mod1 ml can change the stamp assigned to typ
210. st then expr and returns the value of exprs Conditional The expression if expr then expr else expr 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 26 Case expression The expression match expr with pattern gt expr pattern 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 expr evaluates to true if both expr and expr evaluate 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 false Hence the expression expr amp expr behaves exactly as if expr then expr else false The expression expr or expr evaluates to true if one of expr and expr evaluates to true otherwise it evaluates to false The first compon
211. stribution This displays a file dialog box Open the folder where the Caml Light files will reside and click on the Extract button This will re create all files from the distribution in the Caml Light folder To test the installation double click on the application Caml Light The Caml Light output window should display something like 10 gt Caml Light version 0 74 In the Caml Light input window enter 1 2 and press the Return key The Caml Light output window should display gt Caml Light version 0 74 14 2 int 3 Select Quit from the File menu to return to the Finder If you have MPW you can install the batch compilation tools as follows The tools and scripts from the tools folder must reside in a place where MPW will find them as commands There are two ways to achieve this result either copy the files in the tools folder to the Tools or the Scripts folder in your MPW folder or keep the files in the tools folder and add the following line to your UserStartup file assuming Caml Light resides in folder Caml Light on the disk named My HD Set Commands Commands My HD Caml Light tools In either case you now have to edit the camlc script and replace the string Macintosh HD Caml Light 1lib in the first line with the actual pathname of the lib folder For example if you put Caml Light in folder Caml Light on the disk named My HD the first line of camlc should read
212. structors 2 6 Patterns pattern ident pattern as ident pattern pattern typexpr pattern pattern constant neconstr pattern pattern pattern pattern label pattern label 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 Assodativiiy Constructor application 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 identifiers to values Variable patterns A pattern that consists in an identifier matches any value binding the identifier to the value The pattern _ also matches any value but does not bind any identifier Chapter 2 The core Caml Light language 21 Alias patterns The pattern pattern as ident matches the same values as pattern If the matching against pattern is successful the identifier ident 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
213. t 2 3 Values This section describes the kinds of values that are manipulated by Caml Light programs 2 3 1 Base values Integer numbers Integer values are integer numbers from 2 to 2 1 that is 1073741824 to 1073741823 Implementations may support a wider range of integer values Floating point numbers Floating point values are numbers in floating point representation Everything about floating point values is implementation dependent including the range of representable numbers the number of significant digits and the way floating point results are rounded 18 Characters Character values are represented as 8 bit integers between 0 and 255 Character codes between 0 and 127 are interpreted following the ASCII standard The interpretation of character codes between 128 and 255 is implementation dependent Character strings String values are finite sequences of characters Implementations must support strings up to 216 1 characters in length 65535 characters Implementations may support longer strings 2 3 2 Tuples Tuples of values are written 21 0 standing for the n tuple of values v to vn Tuples of up to 214 _ 1 elements 16383 elements must be supported though implementations may support tuples with more elements 2 3 3 Records Record values are labeled tuples of values The record value written label v1 label vn associates the value v to the record label label for i
214. t int gt unit Change the owner uid and owner gid of the named file value fchown file_descr gt int gt int gt unit Change the owner uid and owner gid of an opened file value umask int gt int Set the process creation mask and return the previous mask value access string gt access_permission list gt unit Check that the process has the given permissions over the named file Raise Unix_error otherwise File descriptor hacking value fcntl_int file_descr gt int gt int gt int Interface to fcntl1 in the case where the argument is an integer The first integer argument is the command code the second is the integer parameter value fcntl_ptr file_descr gt int gt string gt int Interface to fcntl in the case where the argument is a pointer The integer argument is the command code A pointer to the string argument is passed as argument to the command Chapter 16 The unix library Unix system calls 179 Directories value mkdir string gt file_perm gt unit Create a directory with the given permissions value rmdir string gt unit Remove an empty directory value chdir string gt unit Change the process working directory value getcwd unit gt string Return the name of the current working directory type dir_handle The type of descriptors over opened directories value opendir string gt dir_handle Open a descriptor on a directory value readdir dir_handle gt stri
215. t unit 1 curses_endwin refresh unit gt unit 1 curses_refresh wrefresh window gt unit 1 curses_wrefresh newwin int gt int gt int gt int gt window 4 curses_newwin mvwin window gt int gt int gt unit 3 curses_mvwin addch char gt unit 1 curses_addch mvwaddch window gt int gt int gt char gt unit 4 curses_mvwaddch addstr string gt unit 1 curses_addstr mvwaddstr window gt int gt int gt string gt unit 4 curses_mvwaddstr lots more omitted To compile this interface camlc 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 unit value unit return value initscr OK to coerce directly from WINDOW to value since that s a block created by malloc value curses_wrefresh win value win wrefresh WINDOW win return Val_unit value curses_newwin nlines ncols x0 y0 value nlines ncols x0 y0 return value newwin Int_val nlines Int_val ncols value Int_val x0 Int_val y0 curses_addch c value c Chapter 12 Interfacing C with Caml Light 109 addch Int_val c Characters are encoded like integers return Val_unit value curses_addstr s value s
216. t 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 9 3 1 Getting help The Caml Light 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 9 The debugger camldebug 81 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 9 3 2 Accessing the debugger state set variable value Set the debugger variable variable to 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 9 4 Executing a pr
217. t x y width w and heigth h with the current color value fill_poly int int vect gt unit Fill the given polygon with the current color The array contains the coordinates of the vertices of the polygon value 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 draw_arc value 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 draw_ellipse value fill_circle int gt int gt int gt unit Fill a circle with the current color The parameters are the same as for draw_circle Images type image The abstract type for images in internal representation Externally images are represented as matrices of colors value 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 value make_image color vect vect 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 value dump_image imag
218. t_addr 185 string_of_int 122 string_of_num 194 sub_float 117 sub_int 120 sub_num 192 sub_string 132 sub_vect 134 substitute_first 199 subtract 129 succ 120 succ_num 193 symbol_end 153 symbol_start 153 symlink 180 sys module 159 Sys_error exception 159 sys_print_num 194 system 175 system_command 161 take 156 Index to the library tan 118 tanh 118 tcdrain 190 tcflow 190 tcflush 190 tcgetattr 190 tcsendbreak 190 tcsetattr 190 text_size 166 time 161 183 times 183 t1 128 toplevel module 55 trace 56 transp 167 truncate 176 umask 178 union 129 158 unix module 171 Unix_error exception 173 unlink 177 untrace 57 utimes 183 vect module 134 vect_assign 134 vect_item 134 vect_length 134 vect_of_list 135 verbose_mode 57 wait 174 wait_next_event 168 waitopt 174 waitpid 174 white 165 write 176 yellow 165 215 Index of keywords and see let type exception value where when 36 as 21 where 37 while 26 begin 22 23 with see match try do see while for done see while for downto see for else see if end 22 23 exception 31 32 for 22 26 fun 22 function 22 35 if 22 25 in see let let 22 24 match 22 26 35 mutable 30 37 not 22 of see type exception or 22 26 prefix 22 28 39 rec see let where then see if to see for try 22 27 type 30 32 value 32 216
219. t_left int gt int gt int n lsl m or equivalently lshift_left n m shifts n to the left by m bits value prefix lsr int gt int gt int 121 n lsr m shifts n to the right by m bits This is a logical shift zeroes are inserted regardless of sign value prefix asr int gt int gt int value lshift_right int gt int gt int n asr m or equivalently lshift_right n m shifts n to the right by m bits This is an arithmetic shift the sign bit is replicated 122 Conversion functions value string_of_int int gt string Convert the given integer to its decimal representation value int_of_string string gt int Convert the given string to an integer in decimal by default or in hexadecimal octal or binary if the string begins with Ox Oo or Ob Raise Failure int_of_string if the given string is not a valid representation of an integer 13 11 io buffered input and output type in_channel type out_channel The abstract types of input channels and output channels exception End_of_file Raised when an operation cannot complete because the end of the file has been reached value stdin in_channel value std_in in_channel value stdout out_channel value std_out out_channel value stderr out_channel value std_err out_channel The standard input standard output and standard error output for the process std_in std_out and std_err are respectively synonymous with stdin stdout and stderr
220. tatus 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 Chapter 15 The graphics library 169 Mouse and keyboard polling value 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 mouse_pos returns a point outside of the range O size_xQ 1 0 size_y 1 value button_down unit gt bool Return true if the mouse button is pressed false otherwise value read_key unit gt char Wait for a key to be pressed and return the corresponding character Keypresses are queued value key_pressed unit gt bool Return true if a keypress is available that is if read_key would not block Sound value sound int gt int gt unit sound freq dur plays a sound at frequency freq in hertz for a duration dur in milliseconds On the Macintosh the frequency is rounded to the nearest note in the equal tempered scale 170 Chapter 16 The unix library Unix system calls The unix library distributed in contrib libunix mak
221. te characters The two double quotes enclose a sequence of either characters different from and or escape sequences from the table below Character denoted backslash double quote newline LF return CR horizontal tabulation TAB backspace BS the character with ASCII code ddd in decimal Implementations must support string literals up to 216 1 characters in length 65535 charac ters 16 Keywords The identifiers below are reserved as keywords and cannot be employed otherwise and as begin do done downto else end exception for fun function if in let match mutable not of or prefix rec then to try type value where while with The following character sequences are also keywords amp C gt lt o lt lt lt lt lt 5 kD gt gt gt gt I d Il 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 longest first token 2 2 Global names Global names are used to denote value variables value constructors constant or non constant type constructors and record labels Internally a global name consists of two parts the name of the defining module the module name and the name of the global inside that module the local name The two parts o
222. 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 regexp Concatenation Match the concatenation of two strings the first matching regexp the second matching regexp regexp Match the same strings as regexp Concerning the precedences of operators and have highest precedence followed by then concatenation then alternation 8 2 4 Actions The actions are arbitrary Caml Light expressions They are evaluated in a context where the identifier 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__get_lexeme lexbuf Return the matched string lexing__get_lexeme_char lexbuf n Return the n character in the matched string The first character corresponds to n 0 lexing__get_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__get_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 74 entrypoint L
223. tialized with the double d e 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 e copy_string_array p allocates an array of strings copied from the pointer to a string array p a char x 12 4 5 Raising exceptions C functions cannot raise arbitrary exceptions However two functions are provided to raise two standard exceptions e failwith s where s is a null terminated C string with type char raises exception Failure with argument s e invalid_argument s where s is a null terminated C string with type char raises ex ception Invalid_argument with argument s 12 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 106 Rule 1 After a structured block a block with tag less than No_scan_tag is allocated 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 or alloc_tuple filling is performed by direct assignment to the fields of the block
224. tion Exit This exception is not raised by any library function It is provided for use in your programs value failwith string gt a Raise exception Failure with the given string value invalid_arg string gt a Raise exception Invalid_argument with the given string Chapter 13 The core library 13 6 fchar character operations without sanity checks This module implements the same functions as the char module but does not perform bound checks on the arguments of the functions The functions are therefore faster than those in the char module but calling these functions with incorrect parameters that is parameters that would cause the Invalid_argument exception to be raised by the corresponding functions in the char module can crash the program 13 7 float operations on floating point numbers value int_of_float float gt int 117 Truncate the given float to an integer value The result is unspecified if it falls outside the range of representable integers value float_of_int int gt float Convert an integer to floating point value minus float gt float value minus_float float gt float Unary negation value prefix float gt float gt float value prefix float gt float gt float value add_float float gt float gt float Addition value prefix float gt float gt float value prefix float gt float gt float value sub_float float gt float gt
225. toplevel system is available under the name caml exe It runs under MSDOS as well as under Windows in a DOS window No editing facilities are provided Options The following command line options are recognized by the caml or camllight commands 8 Start the toplevel system in debugging mode This mode gives access to values and types that are local to a module that is not exported by the interface of the module When debugging mode is off these local objects are not accessible attempts to access them produce an Unbound identifier error When debugging mode is on these objects become visible just like the objects that are exported in the module interface In particular values of abstract types are printed using their concrete representations and the functions local to a module can be traced see the trace function in section 5 2 This applies only to the modules that have been compiled in debugging mode either by the batch compiler with the g option or by the toplevel system in debugging mode that is those modules that have an associated Zix file I directory Add the given directory to the list of directories searched for compiled interface files zi and compiled object code files zo By default the current directory is searched first then the standard library directory Directories added with I are searched after the current directory Chapter 5 The toplevel system camllight 55 but before the standa
226. tputs 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 4 character followed by optional flags and field widths followed by one conversion character The conversion characters and their meanings are d or i convert an integer argument to signed decimal Chapter 14 The standard library 155 u convert an integer argument to unsigned decimal x convert an integer argument to unsigned hexadecimal using lowercase letters X convert an integer argument to unsigned hexadecimal using uppercase letters i insert a string argument c insert a character argument f convert a floating point argument to decimal notation in the style dddd ddd 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 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 argument must therefore have type out_channel gt b gt unit and the second b The output produced by the
227. tream_from f gt but is implemented more efficiently value stream_of_string string gt char stream stream_of_string s returns the stream of the characters in string s value stream_of_channel in_channel gt char stream stream_of_channel ic returns the stream of characters read on channel ic value do_stream a gt unit gt a stream gt unit do_stream f s scans the whole stream s applying the function f in turn to each terminal encountered value stream_check a gt bool gt a stream gt a stream_check p returns the parser which returns the first terminal of the stream if the predicate p returns true on this terminal and raises Parse_failure otherwise value end_of_stream a stream gt unit Return iff the stream is empty and raise Parse_failure otherwise value stream_get a stream gt a a stream stream_get s return the first element of the stream s and a stream containing the remaining elements of s Raise Parse_failure if the stream is empty The stream s is not modified This function makes it possible to access a stream non destructively 132 13 16 string string operations value string_length string gt int Return the length number of characters of the given string value nth_char string gt int gt char nth_char s nreturns character number n in string s The first character is character number 0 The last character is character number string_length
228. try h_name string h_aliases string vect h_addrtype socket_domain h_addr_list inet_addr vect Structure of entries in the hosts database type protocol_entry p_name string p_aliases string vect p_proto int Structure of entries in the protocols database 188 type service_entry s_name string s_aliases string vect S_port int S_proto string Structure of entries in the services database value gethostname unit gt string Return the name of the local host value gethostbyname string gt host_entry Find an entry in hosts with the given name or raise Not_found value gethostbyaddr inet_addr gt host_entry Find an entry in hosts with the given address or raise Not_found value getprotobyname string gt protocol_entry Find an entry in protocols with the given name or raise Not_found value getprotobynumber int gt protocol_entry Find an entry in protocols with the given protocol number or raise Not_found value getservbyname string gt string gt service_entry Find an entry in services with the given name or raise Not_found value getservbyport int gt string gt service_entry Find an entry in services with the given service number or raise Not_found 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 pa
229. ts a simple standard lexical analyzer presented as a function from character streams to token streams It implements roughly the lexical conventions of Caml but is parameterized by the set of keywords of your language 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 backquotes 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 value make_lexer string list gt char stream gt token stream 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 Example a lexer suitable for a desk calculator is obtained by let lexer make lexer ae A SL ee et S0 neu nyu The associated parser would be a function from token stream to for instance int and would have rul
230. ty 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 line 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 value close_box unit gt unit Close the most recently opened pretty printing box Formatting functions value print_string string gt unit print_string str prints str in the current box value 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 value print_int int gt unit Print an integer in the current box value print_float float gt unit Print a floating point number in the current box value print_char char gt unit Print a character in the current box value print_bool bool gt unit Print an boolean in the current box 142 Break hints value 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 value print_cut unit gt unit print_cut is used to mark a good break po
231. typexpr mutable ident typexpr Type definitions bind type constructors to data types either variant types record types type abbreviations or abstract data types 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 an identifier possibly preceded by one or several type parameters and followed by a data type description The identifier is the local name of the type constructor being defined The module name for this type constructor is the name of the module being compiled 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 These type parameters can appear in the type expressions of the right hand side of the definition Variant types The type definition typeparams ident constr decl constr decl defines a variant type The constructor declarations constr decl constr decl describe the constructors associated to this variant type The constructor declaration ident of typexpr declares the local name ident in the module being compiled as a non constant constructor whose argument has type typexpr The constructor declaration ident declares the local name ident in the modu
232. ues 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 Non generalized type variables in a type cause no difficulties inside a given compilation unit the contents of a m1 file or an interactive session but they cannot be allowed in types written in a zi compiled interface file because they could be used inconsistently in other compilation units Therefore the compiler flags an error when a ml implementation without a mli interface defines a global variable name whose type contains non generalized type variables There are two solutions to this problem e Add a type constraint or a mli interface to give a monomorphic type without type variables to name For instance instead of writing let sort_int_list sort prefix lt inferred type a list gt a list with a not generalized write let sort_int_list sort prefix 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 map vect_length inferred type a vect list gt int list with a not generalized write let map_length lv map vect_length lv mod__name is referenced before being defined This error appears when trying to link an incomplete or incorrectly ordered set of f
233. umber of characters of the given channel This works only for regular files On files of other kinds the result is meaningless value close_out out_channel gt unit Close the given channel flushing all buffered write operations The behavior is unspecified if any of the functions above is called on a closed channel 126 General input functions value 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__Sys_error if the file could not be opened value open_in_bin string gt in_channel Same as open_in 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 open_in value open_in_gen sys__open_flag list gt int gt string gt in_channel open_in_gen mode rights filename opens the file named filename for reading as above The extra arguments mode and rights specify the opening mode and file permissions see sys__open open_in and open_in_bin are special cases of this function value open_descriptor_in int gt in_channel open_descriptor_in fd returns a buffered input channel reading from the file descriptor fd The file descriptor fd must have been previously opened for reading else the behavior is undefined value input_char in_channel gt char Read one cha
234. v 174 execve 174 execvp 174 exists 129 exit 122 160 Exit exception 116 exp 118 Failure exception 116 failwith 116 fchar module 117 fchmod 178 fchown 178 fcntl_int 178 fcntl_ptr 178 filename module 140 fill_arc 167 fill_circle 167 fill_ellipse 167 fill_poly 167 fill_rect 167 fill_string 132 fill_vect 135 find 139 150 153 find_all 150 first_chars 200 flat_map 129 float 157 float module 117 float_of_int 117 209 float_of_num 194 float_of_string 119 floor 118 floor_num 192 flush 124 fold 158 for_all 129 force_newline 142 foreground 165 fork 174 format 200 format module 140 fprint 155 fprintf 146 154 frexp 119 fst 130 fstat 177 fstring module 119 ftruncate 176 full_init 157 full_major 149 fvect module 119 gc module 147 ge_float 118 ge_int 121 ge_num 193 ge_string 133 genlex module 149 get 148 get_approx_printing 195 get_ellipsis_text 144 get_error_when_null_denominator 194 get_floating_precision 195 get_formatter_output_functions 144 get_image 168 get_lexeme 152 get_lexeme_char 152 get_lexeme_end 152 get_lexeme_start 152 get_margin 142 get_max_boxes 143 get_max_indent 143 get_normalize_ratio 195 get_normalize_ratio_when_printing 195 210 getcwd 179 getegid 184 getenv 161 geteuid 184 getgid 184 getgrgid 185 getgrnam 185 getgroups 184 gethostbyaddr 188 gethostbynam
235. value new unit gt at Return a new queue initially empty value add a gt a t gt unit add x q adds the element x at the end of the queue q value take a t gt a take q removes and returns the first element in queue q or raises Empty if the queue is empty value peek a t 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 value clear a t gt unit Discard all elements from a queue value length a t gt int Return the number of elements in a queue value iter a gt unit gt at 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 Chapter 14 The standard library 157 14 14 random pseudo random number generator value init int gt unit Initialize the generator using the argument as a seed The same seed will always yield the same sequence of numbers value full_init int vect gt unit Same as init but takes more data as seed It is not useful to give more than 55 integers value int int gt int random__int bound returns a random number between 0 inclusive and bound exclusive bound must be positive and smaller than 23 value float float gt float random__float bound returns a random number between 0 inclusive and bound exclusive 14 15 set sets over ordered types
236. writing mylib zo camllibr o mylib zo windows zo images zo buttons zo tmplib zo Then copy mylib zi and mylib zo to a place accessible to the library users The other zi and zo files need not be copied 70 Chapter 8 Lexer and parser generators camllex camlyacc This chapter describes two program generators camllex that produces a lexical analyzer from a set of regular expressions with associated semantic actions and camlyacc 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 programming environments This chapter assumes a working knowledge of lex and yacc while it describes the input syntax for camllex and camlyacc 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 Compiler design in C by Holub Prentice Hall 1990 or Lex amp Yacc by Mason and Brown O Reilly 1990 Streams and stream matching as described in section 3 1 provide an alternative way to write lexers and parsers The stream matching technique is more powerful than the combination of camllex and camlyacc in some cases higher order parsers but less powerful in other cases prece dences Ch
237. xicographic extension of f 140 14 3 filename operations on file names value current_dir_name string The conventional name for the current directory e g in Unix value concat string gt string gt string concat dir file returns a file name that designates file file in directory dir value is_absolute string gt bool Return true if the file name is absolute or starts with an explicit reference to the current directory or in Unix and false if it is relative to the current directory value check_suffix string gt string gt bool check_suffix name suff returns true if the filename name ends with the suffix suff value 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 value basename string gt string value dirname 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 references to basename name which is a relative file name designate the same file as name before the call to chdir 14 4 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 inde
238. y More precisely the dump file camlpro dump is written when the io__exit function is called The linker called with the p option adds io__exit O as the last phrase of the bytecode executable in case the original program never calls io__exit However if the program terminates with an uncaught exception the dump file will not be produced 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 10 3 Printing profiling information The camlpro command produces a source listing of the program modules where execution counts have been inserted as comments For instance camlpro 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 camlpro compiler options stdlib I include 0 open i lang See chapter 4 for the detailed usage f dumpfile Specifies an alternate dump file of profiling information F string Specifies an additional string to be output with profiling information By default camlpro will annotate progams with comments of the form n where n is the counter value for a profiling point With opti
239. y qualified global names by looking at a list of opened modules that define the same name see section 9 8 5 for how to open modules in the debugger The completion follows the same rules as in the Caml Light language see section 2 2 print variables Print the values of the given variables match variable pattern Match the value of the given variable against a pattern and print the values bound to the identifiers in the pattern The syntax of patterns for the match command extends the one for Caml Light patterns 86 pattern ident pattern neconstr pattern pattern pattern pattern label pattern label pattern pattern pattern pattern pattern integer literal pattern gt pattern The pattern ident where ident is an identifier matches any value and binds the identifier to this value The pattern n pattern matches a list a vector or a tuple whose n th element matches pattern The pattern gt pattern matches any constructed value whose argument matches pattern regardless of the constructor it is a shortcut for skipping a constructor Example assuming the value of a is Constr x 1 2 3 4 the command match a gt x 2 k prints k 3 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 9 8 Controlling the debugger 9 8 1 Setting the program name and arguments
240. y mode O_TEXT open in text mode The commands for open value exit int gt a Terminate the program and return the given status code to the operating system In contrast with the function exit from module io this exit function does not flush the standard output and standard error channels Chapter 14 The standard library 161 value open string gt open_flag list gt file_perm gt int Open a file The second argument is the opening mode The third argument is the permissions to use if the file must be created The result is a file descriptor opened on the file value close int gt unit Close a file descriptor value remove string gt unit Remove the given file name from the file system value rename string gt string gt unit Rename a file The first argument is the old name and the second is the new name value getenv string gt string Return the value associated to a variable in the process environment Raise Not_found if the variable is unbound value chdir string gt unit Change the current working directory of the process Note that there is no easy way of getting the current working directory from the operating system value system_command string gt int Execute the given shell command and return its exit code value time unit gt float Return the processor time in seconds used by the program since the beginning of execution exception Break Exception Break is raised

The Caml Light system release 0.74 - The Caml language

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