focal (3) Stdlib.3o.gz

Provided by: ocaml-man_4.08.1-8_all bug

NAME

       Stdlib - The OCaml Standard library.

Module

       Module   Stdlib

Documentation

       Module Stdlib
        : sig end

       The OCaml Standard library.

       This  module  is automatically opened at the beginning of each compilation. All components of this module
       can therefore be referred by their short name, without prefixing them by Stdlib .

       It particular, it provides the  basic  operations  over  the  built-in  types  (numbers,  booleans,  byte
       sequences, strings, exceptions, references, lists, arrays, input-output channels, ...) and the modules .

   Exceptions
       val raise : exn -> 'a

       Raise the given exception value

       val raise_notrace : exn -> 'a

       A faster version raise which does not record the backtrace.

       Since 4.02.0

       val invalid_arg : string -> 'a

       Raise exception Invalid_argument with the given string.

       val failwith : string -> 'a

       Raise exception Failure with the given string.

       exception Exit

       The Exit exception is not raised by any library function.  It is provided for use in your programs.

       exception Match_failure of (string * int * int)

       Exception  raised  when  none of the cases of a pattern-matching apply. The arguments are the location of
       the match keyword in the source code (file name, line number, column number).

       exception Assert_failure of (string * int * int)

       Exception raised when an assertion fails. The arguments are the location of the  assert  keyword  in  the
       source code (file name, line number, column number).

       exception Invalid_argument of string

       Exception  raised  by  library functions to signal that the given arguments do not make sense. The string
       gives some information to the programmer. As a general rule, this exception  should  not  be  caught,  it
       denotes a programming error and the code should be modified not to trigger it.

       exception Failure of string

       Exception  raised  by  library  functions  to  signal that they are undefined on the given arguments. The
       string is meant to give some information to the programmer; you must not  pattern  match  on  the  string
       literal because it may change in future versions (use Failure _ instead).

       exception Not_found

       Exception raised by search functions when the desired object could not be found.

       exception Out_of_memory

       Exception raised by the garbage collector when there is insufficient memory to complete the computation.

       exception Stack_overflow

       Exception  raised  by  the  bytecode interpreter when the evaluation stack reaches its maximal size. This
       often indicates infinite or excessively deep recursion in the user's program. (Not fully  implemented  by
       the native-code compiler.)

       exception Sys_error of string

       Exception  raised  by the input/output functions to report an operating system error. The string is meant
       to give some information to the programmer; you must not pattern match on the string literal  because  it
       may change in future versions (use Sys_error _ instead).

       exception End_of_file

       Exception raised by input functions to signal that the end of file has been reached.

       exception Division_by_zero

       Exception raised by integer division and remainder operations when their second argument is zero.

       exception Sys_blocked_io

       A special case of Sys_error raised when no I/O is possible on a non-blocking I/O channel.

       exception Undefined_recursive_module of (string * int * int)

       Exception  raised  when  an  ill-founded  recursive module definition is evaluated. The arguments are the
       location of the definition in the source code (file name, line number, column number).

   Comparisons
       val (=) : 'a -> 'a -> 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.  Left-associative operator, see Ocaml_operators for
       more information.

       val (<>) : 'a -> 'a -> bool

       Negation of (=) .  Left-associative operator, see Ocaml_operators for more information.

       val (<) : 'a -> 'a -> bool

       See (>=) .  Left-associative operator, see Ocaml_operators for more information.

       val (>) : 'a -> 'a -> bool

       See (>=) .  Left-associative operator,  see Ocaml_operators for more information.

       val (<=) : 'a -> 'a -> bool

       See (>=) .  Left-associative operator,  see Ocaml_operators for more information.

       val (>=) : 'a -> 'a -> bool

       Structural ordering  functions.  These  functions  coincide  with  the  usual  orderings  over  integers,
       characters,  strings, byte sequences and floating-point numbers, and extend them to a total ordering over
       all types.  The ordering is compatible with ( = ) . As in the case of ( =  )  ,  mutable  structures  are
       compared by contents.  Comparison between functional values raises Invalid_argument .  Comparison between
       cyclic  structures  may  not  terminate.   Left-associative  operator,  see  Ocaml_operators   for   more
       information.

       val compare : 'a -> 'a -> int

       compare  x  y  returns  0  if  x  is equal to y , a negative integer if x is less than y , and a positive
       integer if x is greater than y .  The ordering implemented by compare is compatible with  the  comparison
       predicates  =  ,  <  and  > defined above,  with one difference on the treatment of the float value nan .
       Namely, the comparison predicates treat nan as different from any other float  value,  including  itself;
       while  compare  treats nan as equal to itself and less than any other float value.  This treatment of nan
       ensures that compare defines a total ordering relation.

       compare applied to functional values may raise Invalid_argument .  compare applied to  cyclic  structures
       may not terminate.

       The  compare  function  can  be  used  as  the  comparison function required by the Set.Make and Map.Make
       functors, as well as the List.sort and Array.sort functions.

       val min : 'a -> 'a -> 'a

       Return the smaller of the two arguments.  The result is unspecified if one of the arguments contains  the
       float value nan .

       val max : 'a -> 'a -> 'a

       Return  the greater of the two arguments.  The result is unspecified if one of the arguments contains the
       float value nan .

       val (==) : 'a -> 'a -> bool

       e1 == e2 tests for physical equality of e1 and e2 .  On mutable types such as  references,  arrays,  byte
       sequences,  records  with mutable fields and objects with mutable instance variables, e1 == e2 is true if
       and only if physical modification of e1 also affects e2 .  On non-mutable types, the behavior of (  ==  )
       is  implementation-dependent;  however,  it  is  guaranteed  that  e1  ==  e2 implies compare e1 e2 = 0 .
       Left-associative operator,  see Ocaml_operators for more information.

       val (!=) : 'a -> 'a -> bool

       Negation of (==) .  Left-associative operator,  see Ocaml_operators for more information.

   Boolean operations
       val not : bool -> bool

       The boolean negation.

       val (&&) : bool -> bool -> bool

       The boolean 'and'. Evaluation is sequential, left-to-right: in e1 && e2 , e1 is evaluated first,  and  if
       it returns false , e2 is not evaluated at all.  Right-associative operator,  see Ocaml_operators for more
       information.

       val (&) : bool -> bool -> bool

       Deprecated.

       (&&) should be used instead.  Right-associative operator, see Ocaml_operators for more information.

       val (||) : bool -> bool -> bool

       The boolean 'or'. Evaluation is sequential, left-to-right: in e1 || e2 , e1 is evaluated first, and if it
       returns  true  ,  e2  is not evaluated at all.  Right-associative operator,  see Ocaml_operators for more
       information.

       val (or) : bool -> bool -> bool

       Deprecated.

       (||) should be used instead.  Right-associative operator, see Ocaml_operators for more information.

   Debugging
       val __LOC__ : string

       __LOC__ returns the location at which this expression appears in the file currently being parsed  by  the
       compiler, with the standard error format of OCaml: "File %S, line %d, characters %d-%d".

       Since 4.02.0

       val __FILE__ : string

       __FILE__ returns the name of the file currently being parsed by the compiler.

       Since 4.02.0

       val __LINE__ : int

       __LINE__  returns  the line number at which this expression appears in the file currently being parsed by
       the compiler.

       Since 4.02.0

       val __MODULE__ : string

       __MODULE__ returns the module name of the file being parsed by the compiler.

       Since 4.02.0

       val __POS__ : string * int * int * int

       __POS__ returns a tuple (file,lnum,cnum,enum) , corresponding to the location at  which  this  expression
       appears  in the file currently being parsed by the compiler.  file is the current filename, lnum the line
       number, cnum the character position in the line and enum the last character position in the line.

       Since 4.02.0

       val __LOC_OF__ : 'a -> string * 'a

       __LOC_OF__ expr returns a pair (loc, expr) where loc is the location of expr in the file currently  being
       parsed by the compiler, with the standard error format of OCaml: "File %S, line %d, characters %d-%d".

       Since 4.02.0

       val __LINE_OF__ : 'a -> int * 'a

       __LINE_OF__ expr returns a pair (line, expr) , where line is the line number at which the expression expr
       appears in the file currently being parsed by the compiler.

       Since 4.02.0

       val __POS_OF__ : 'a -> (string * int * int * int) * 'a

       __POS_OF__ expr returns a pair (loc,expr) , where loc is a tuple (file,lnum,cnum,enum)  corresponding  to
       the  location  at  which  the expression expr appears in the file currently being parsed by the compiler.
       file is the current filename, lnum the line number, cnum the character position in the line and enum  the
       last character position in the line.

       Since 4.02.0

   Composition operators
       val (|>) : 'a -> ('a -> 'b) -> 'b

       Reverse-application  operator:  x  |>  f  |>  g  is  exactly  equivalent to g (f (x)) .  Left-associative
       operator, see Ocaml_operators for more information.

       Since 4.01

       val (@@) : ('a -> 'b) -> 'a -> 'b

       Application operator: g @@ f @@ x is exactly equivalent to g (f (x)) .  Right-associative  operator,  see
       Ocaml_operators for more information.

       Since 4.01

   Integer arithmetic
       Integers are Sys.int_size bits wide.  All operations are taken modulo 2^ Sys.int_size .  They do not fail
       on overflow.

       val (~-) : int -> int

       Unary negation. You can also write - e instead of ~- e .  Unary operator, see  Ocaml_operators  for  more
       information.

       val (~+) : int -> int

       Unary  addition.  You  can also write + e instead of ~+ e .  Unary operator, see Ocaml_operators for more
       information.

       Since 3.12.0

       val succ : int -> int

       succ x is x + 1 .

       val pred : int -> int

       pred x is x - 1 .

       val (+) : int -> int -> int

       Integer addition.  Left-associative operator, see Ocaml_operators for more information.

       val (-) : int -> int -> int

       Integer subtraction.  Left-associative operator, , see Ocaml_operators for more information.

       val ( * ) : int -> int -> int

       Integer multiplication.  Left-associative operator, see Ocaml_operators for more information.

       val (/) : int -> int -> int

       Integer division.  Raise Division_by_zero if the second argument is 0.  Integer division rounds the  real
       quotient  of  its  arguments  towards  zero.  More precisely, if x >= 0 and y > 0 , x / y is the greatest
       integer less than or equal to the real quotient of x by y .  Moreover, (- x) / y = x / (- y) = - (x /  y)
       .  Left-associative operator, see Ocaml_operators for more information.

       val (mod) : int -> int -> int

       Integer  remainder.  If y is not zero, the result of x mod y satisfies the following properties: x = (x /
       y) * y + x mod y and abs(x mod y) <= abs(y) - 1 .  If y = 0 , x mod y  raises  Division_by_zero  .   Note
       that  x  mod  y  is  negative  only  if  x  < 0 .  Raise Division_by_zero if y is zero.  Left-associative
       operator, see Ocaml_operators for more information.

       val abs : int -> int

       Return the absolute value of the argument.  Note that this may be negative if the argument is min_int .

       val max_int : int

       The greatest representable integer.

       val min_int : int

       The smallest representable integer.

   Bitwise operations
       val (land) : int -> int -> int

       Bitwise logical and.  Left-associative operator, see Ocaml_operators for more information.

       val (lor) : int -> int -> int

       Bitwise logical or.  Left-associative operator, see Ocaml_operators for more information.

       val (lxor) : int -> int -> int

       Bitwise logical exclusive or.  Left-associative operator, see Ocaml_operators for more information.

       val lnot : int -> int

       Bitwise logical negation.

       val (lsl) : int -> int -> int

       n lsl m shifts n to the left by m bits.  The result is unspecified if  m  <  0  or  m  >  Sys.int_size  .
       Right-associative operator, see Ocaml_operators for more information.

       val (lsr) : int -> int -> int

       n  lsr m shifts n to the right by m bits.  This is a logical shift: zeroes are inserted regardless of the
       sign of n .  The result is unspecified if m < 0 or m > Sys.int_size .   Right-associative  operator,  see
       Ocaml_operators for more information.

       val (asr) : int -> int -> int

       n  asr  m shifts n to the right by m bits.  This is an arithmetic shift: the sign bit of n is replicated.
       The result is unspecified if m < 0 or m > Sys.int_size .  Right-associative operator, see Ocaml_operators
       for more information.

   Floating-point arithmetic
       OCaml's  floating-point  numbers  follow the IEEE 754 standard, using double precision (64 bits) numbers.
       Floating-point operations never raise an  exception  on  overflow,  underflow,  division  by  zero,  etc.
       Instead, special IEEE numbers are returned as appropriate, such as infinity for 1.0 /. 0.0 , neg_infinity
       for -1.0 /. 0.0 , and nan ('not a number') for 0.0 /. 0.0 .  These special numbers then propagate through
       floating-point  computations  as  expected:  for  instance,  1.0  /. infinity is 0.0 , and any arithmetic
       operation with nan as argument returns nan as result.

       val (~-.)  : float -> float

       Unary negation. You can also write -. e instead of ~-. e .  Unary operator, see Ocaml_operators for  more
       information.

       val (~+.)  : float -> float

       Unary  addition. You can also write +. e instead of ~+. e .  Unary operator, see Ocaml_operators for more
       information.

       Since 3.12.0

       val (+.)  : float -> float -> float

       Floating-point addition.  Left-associative operator, see Ocaml_operators for more information.

       val (-.)  : float -> float -> float

       Floating-point subtraction.  Left-associative operator, see Ocaml_operators for more information.

       val ( *. ) : float -> float -> float

       Floating-point multiplication.  Left-associative operator, see Ocaml_operators for more information.

       val (/.)  : float -> float -> float

       Floating-point division.  Left-associative operator, see Ocaml_operators for more information.

       val ( ** ) : float -> float -> float

       Exponentiation.  Right-associative operator, see Ocaml_operators for more information.

       val sqrt : float -> float

       Square root.

       val exp : float -> float

       Exponential.

       val log : float -> float

       Natural logarithm.

       val log10 : float -> float

       Base 10 logarithm.

       val expm1 : float -> float

       expm1 x computes exp x -. 1.0 , giving numerically-accurate results even if x is close to 0.0 .

       Since 3.12.0

       val log1p : float -> float

       log1p x computes log(1.0 +. x) (natural logarithm), giving numerically-accurate  results  even  if  x  is
       close to 0.0 .

       Since 3.12.0

       val cos : float -> float

       Cosine.  Argument is in radians.

       val sin : float -> float

       Sine.  Argument is in radians.

       val tan : float -> float

       Tangent.  Argument is in radians.

       val acos : float -> float

       Arc  cosine.   The argument must fall within the range [-1.0, 1.0] .  Result is in radians and is between
       0.0 and pi .

       val asin : float -> float

       Arc sine.  The argument must fall within the range [-1.0, 1.0] .  Result is in  radians  and  is  between
       -pi/2 and pi/2 .

       val atan : float -> float

       Arc tangent.  Result is in radians and is between -pi/2 and pi/2 .

       val atan2 : float -> float -> float

       atan2 y x returns the arc tangent of y /. x .  The signs of x and y are used to determine the quadrant of
       the result.  Result is in radians and is between -pi and pi .

       val hypot : float -> float -> float

       hypot x y returns sqrt(x *. x + y *. y) , that is,  the  length  of  the  hypotenuse  of  a  right-angled
       triangle  with sides of length x and y , or, equivalently, the distance of the point (x,y) to origin.  If
       one of x or y is infinite, returns infinity even if the other is nan .

       Since 4.00.0

       val cosh : float -> float

       Hyperbolic cosine.  Argument is in radians.

       val sinh : float -> float

       Hyperbolic sine.  Argument is in radians.

       val tanh : float -> float

       Hyperbolic tangent.  Argument is in radians.

       val ceil : float -> float

       Round above to an integer value.  ceil f returns the least integer value greater than or  equal  to  f  .
       The result is returned as a float.

       val floor : float -> float

       Round  below  to  an integer value.  floor f returns the greatest integer value less than or equal to f .
       The result is returned as a float.

       val abs_float : float -> float

       abs_float f returns the absolute value of f .

       val copysign : float -> float -> float

       copysign x y returns a float whose absolute value is that of x and whose sign is that of y .  If x is nan
       , returns nan .  If y is nan , returns either x or -. x , but it is not specified which.

       Since 4.00.0

       val mod_float : float -> float -> float

       mod_float a b returns the remainder of a with respect to b .  The returned value is a -. n *. b , where n
       is the quotient a /. b rounded towards zero to an integer.

       val frexp : float -> 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 by f = x *. 2 ** n and
       0.5 <= x < 1.0 .

       val ldexp : float -> int -> float

       ldexp x n returns x *. 2 ** n .

       val modf : float -> float * float

       modf f returns the pair of the fractional and integral part of f .

       val float : int -> float

       Same as float_of_int .

       val float_of_int : int -> float

       Convert an integer to floating-point.

       val truncate : float -> int

       Same as int_of_float .

       val int_of_float : float -> int

       Truncate the given floating-point number to an integer.  The result is unspecified if the argument is nan
       or falls outside the range of representable integers.

       val infinity : float

       Positive infinity.

       val neg_infinity : float

       Negative infinity.

       val nan : float

       A special floating-point value denoting the result of an undefined operation such as 0.0 /. 0.0 .  Stands
       for 'not a number'.  Any floating-point operation with nan as argument returns nan  as  result.   As  for
       floating-point  comparisons,  =  ,  <  , <= , > and >= return false and <> returns true if one or both of
       their arguments is nan .

       val max_float : float

       The largest positive finite value of type float .

       val min_float : float

       The smallest positive, non-zero, non-denormalized value of type float .

       val epsilon_float : float

       The difference between 1.0 and the smallest exactly representable floating-point number greater than  1.0
       .

       type fpclass =
        | FP_normal  (* Normal number, none of the below
        *)
        | FP_subnormal  (* Number very close to 0.0, has reduced precision
        *)
        | FP_zero  (* Number is 0.0 or -0.0
        *)
        | FP_infinite  (* Number is positive or negative infinity
        *)
        | FP_nan  (* Not a number: result of an undefined operation
        *)

       The five classes of floating-point numbers, as determined by the classify_float function.

       val classify_float : float -> fpclass

       Return the class of the given floating-point number: normal, subnormal, zero, infinite, or not a number.

   String operations
       More string operations are provided in module String .

       val (^) : string -> string -> string

       String concatenation.  Right-associative operator, see Ocaml_operators for more information.

   Character operations
       More character operations are provided in module Char .

       val int_of_char : char -> int

       Return the ASCII code of the argument.

       val char_of_int : int -> char

       Return  the  character  with the given ASCII code.  Raise Invalid_argument char_of_int if the argument is
       outside the range 0--255.

   Unit operations
       val ignore : 'a -> unit

       Discard the value of its argument and return () .  For instance, ignore(f x) discards the result  of  the
       side-effecting function f .  It is equivalent to f x; () , except that the latter may generate a compiler
       warning; writing ignore(f x) instead avoids the warning.

   String conversion functions
       val string_of_bool : bool -> string

       Return the string representation of a boolean. As the returned values may be shared, the user should  not
       modify them directly.

       val bool_of_string_opt : string -> bool option

       Convert the given string to a boolean.

       Return None if the string is not true or false .

       Since 4.05

       val bool_of_string : string -> bool

       Same as bool_of_string_opt , but raise Invalid_argument bool_of_string instead of returning None .

       val string_of_int : int -> string

       Return the string representation of an integer, in decimal.

       val int_of_string_opt : string -> int option

       Convert  the  given  string  to  an integer.  The string is read in decimal (by default, or if the string
       begins with 0u ), in hexadecimal (if it begins with 0x or 0X ), in octal (if it begins with 0o or  0O  ),
       or in binary (if it begins with 0b or 0B ).

       The  0u  prefix  reads  the  input  as  an unsigned integer in the range [0, 2*max_int+1] .  If the input
       exceeds max_int it is converted to the signed integer min_int + input - max_int - 1 .

       The _ (underscore) character can appear anywhere in the string and is ignored.

       Return None if the given string is  not  a  valid  representation  of  an  integer,  or  if  the  integer
       represented exceeds the range of integers representable in type int .

       Since 4.05

       val int_of_string : string -> int

       Same as int_of_string_opt , but raise Failure int_of_string instead of returning None .

       val string_of_float : float -> string

       Return the string representation of a floating-point number.

       val float_of_string_opt : string -> float option

       Convert  the  given  string  to  a  float.   The string is read in decimal (by default) or in hexadecimal
       (marked by 0x or 0X ).

       The format of decimal floating-point numbers is [-] dd.ddd (e|E) [+|-] dd , where d stands for a  decimal
       digit.

       The format of hexadecimal floating-point numbers is [-] 0(x|X) hh.hhh (p|P) [+|-] dd , where h stands for
       an hexadecimal digit and d for a decimal digit.

       In both cases, at least one of the integer and fractional parts must  be  given;  the  exponent  part  is
       optional.

       The _ (underscore) character can appear anywhere in the string and is ignored.

       Depending  on  the  execution platforms, other representations of floating-point numbers can be accepted,
       but should not be relied upon.

       Return None if the given string is not a valid representation of a float.

       Since 4.05

       val float_of_string : string -> float

       Same as float_of_string_opt , but raise Failure float_of_string instead of returning None .

   Pair operations
       val fst : 'a * 'b -> 'a

       Return the first component of a pair.

       val snd : 'a * 'b -> 'b

       Return the second component of a pair.

   List operations
       More list operations are provided in module List .

       val (@) : 'a list -> 'a list -> 'a list

       List concatenation.  Not tail-recursive (length of the first argument).  Right-associative operator,  see
       Ocaml_operators for more information.

   Input/output
       Note: all input/output functions can raise Sys_error when the system calls they invoke fail.

       type in_channel

       The type of input channel.

       type out_channel

       The type of output channel.

       val stdin : in_channel

       The standard input for the process.

       val stdout : out_channel

       The standard output for the process.

       val stderr : out_channel

       The standard error output for the process.

   Output functions on standard output
       val print_char : char -> unit

       Print a character on standard output.

       val print_string : string -> unit

       Print a string on standard output.

       val print_bytes : bytes -> unit

       Print a byte sequence on standard output.

       Since 4.02.0

       val print_int : int -> unit

       Print an integer, in decimal, on standard output.

       val print_float : float -> unit

       Print a floating-point number, in decimal, on standard output.

       val print_endline : string -> unit

       Print a string, followed by a newline character, on standard output and flush standard output.

       val print_newline : unit -> 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
       val prerr_char : char -> unit

       Print a character on standard error.

       val prerr_string : string -> unit

       Print a string on standard error.

       val prerr_bytes : bytes -> unit

       Print a byte sequence on standard error.

       Since 4.02.0

       val prerr_int : int -> unit

       Print an integer, in decimal, on standard error.

       val prerr_float : float -> unit

       Print a floating-point number, in decimal, on standard error.

       val prerr_endline : string -> unit

       Print a string, followed by a newline character on standard error and flush standard error.

       val prerr_newline : unit -> unit

       Print a newline character on standard error, and flush standard error.

   Input functions on standard input
       val read_line : unit -> string

       Flush standard output, then read characters from standard input until a newline character is encountered.
       Return the string of all characters read, without the newline character at the end.

       val read_int_opt : unit -> int option

       Flush standard output, then read one line from standard input and convert it to an integer.

       Return None if the line read is not a valid representation of an integer.

       Since 4.05

       val read_int : unit -> int

       Same as read_int_opt , but raise Failure int_of_string instead of returning None .

       val read_float_opt : unit -> float option

       Flush standard output, then read one line from standard input and convert it to a floating-point number.

       Return None if the line read is not a valid representation of a floating-point number.

       Since 4.05.0

       val read_float : unit -> float

       Same as read_float_opt , but raise Failure float_of_string instead of returning None .

   General output functions
       type open_flag =
        | Open_rdonly  (* open for reading.
        *)
        | Open_wronly  (* open for writing.
        *)
        | Open_append  (* open for appending: always write at end of file.
        *)
        | Open_creat  (* create the file if it does not exist.
        *)
        | Open_trunc  (* empty the file if it already exists.
        *)
        | Open_excl  (* fail if Open_creat and the file already exists.
        *)
        | Open_binary  (* open in binary mode (no conversion).
        *)
        | Open_text  (* open in text mode (may perform conversions).
        *)
        | Open_nonblock  (* open in non-blocking mode.
        *)

       Opening modes for open_out_gen and open_in_gen .

       val open_out : string -> out_channel

       Open  the  named  file  for  writing,  and  return  a  new output channel on that file, positioned 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.

       val open_out_bin : string -> 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 distinguish between text mode and  binary  mode,  this  function
       behaves like open_out .

       val open_out_gen : open_flag list -> int -> string -> out_channel

       open_out_gen  mode perm filename opens the named file for writing, as described above. The extra argument
       mode specifies the opening mode. The extra argument perm specifies the file permissions, in case the file
       must be created.  open_out and open_out_bin are special cases of this function.

       val flush : out_channel -> unit

       Flush the buffer associated with the given output channel, performing all pending writes on that channel.
       Interactive programs must be careful about flushing standard output and standard error at the right time.

       val flush_all : unit -> unit

       Flush all open output channels; ignore errors.

       val output_char : out_channel -> char -> unit

       Write the character on the given output channel.

       val output_string : out_channel -> string -> unit

       Write the string on the given output channel.

       val output_bytes : out_channel -> bytes -> unit

       Write the byte sequence on the given output channel.

       Since 4.02.0

       val output : out_channel -> bytes -> int -> int -> unit

       output oc buf pos len writes len characters from byte sequence buf , starting at  offset  pos  ,  to  the
       given output channel oc .  Raise Invalid_argument output if pos and len do not designate a valid range of
       buf .

       val output_substring : out_channel -> string -> int -> int -> unit

       Same as output but take a string as argument instead of a byte sequence.

       Since 4.02.0

       val output_byte : out_channel -> int -> 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.

       val output_binary_int : out_channel -> int -> unit

       Write  one integer in binary format (4 bytes, big-endian) on the given output channel.  The given integer
       is taken modulo 2^32.  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 OCaml.

       val output_value : out_channel -> 'a -> 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 . See  the
       description  of  module  Marshal  for more information.  output_value is equivalent to Marshal.to_channel
       with an empty list of flags.

       val seek_out : out_channel -> int -> 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.

       val pos_out : out_channel -> int

       Return  the  current  writing  position for the given channel.  Does not work on channels opened with the
       Open_append flag (returns unspecified results).

       val out_channel_length : out_channel -> int

       Return the size (number of characters) of the regular file on which the given channel is opened.  If  the
       channel is opened on a file that is not a regular file, the result is meaningless.

       val close_out : out_channel -> unit

       Close  the  given  channel,  flushing  all buffered write operations.  Output functions raise a Sys_error
       exception when they are applied to a closed output channel, except close_out and flush , which do nothing
       when  applied  to  an  already  closed channel.  Note that close_out may raise Sys_error if the operating
       system signals an error when flushing or closing.

       val close_out_noerr : out_channel -> unit

       Same as close_out , but ignore all errors.

       val set_binary_mode_out : out_channel -> bool -> unit

       set_binary_mode_out oc true sets the channel oc to binary mode: no translations take place during output.
       set_binary_mode_out  oc  false  sets the channel oc to text mode: depending on the operating system, some
       translations may take place during output.  For instance, under Windows, end-of-lines will be  translated
       from  \n  to  \r\n .  This function has no effect under operating systems that do not distinguish between
       text mode and binary mode.

   General input functions
       val open_in : string -> in_channel

       Open the named file for reading, and return a new input channel on that file, positioned at the beginning
       of the file.

       val open_in_bin : string -> 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 .

       val open_in_gen : open_flag list -> int -> string -> in_channel

       open_in_gen  mode perm filename opens the named file for reading, as described above. The extra arguments
       mode and perm specify the opening mode and file permissions.  open_in and open_in_bin are  special  cases
       of this function.

       val input_char : in_channel -> char

       Read  one  character  from the given input channel.  Raise End_of_file if there are no more characters to
       read.

       val input_line : in_channel -> 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.

       val input : in_channel -> bytes -> int -> int -> int

       input ic buf pos len reads up to len characters from the given channel ic , storing them in byte sequence
       buf  , starting at character number pos .  It returns the actual number of characters read, between 0 and
       len (inclusive).  A return value of 0 means that the end of file was reached.  A return value  between  0
       and  len  exclusive  means  that  not  all  requested  len  characters  were read, either because no more
       characters were available at that time, or because the implementation found it convenient to do a partial
       read;  input  must  be called again to read the remaining characters, if desired.  (See also really_input
       for reading exactly len characters.)  Exception Invalid_argument input is raised if pos and  len  do  not
       designate a valid range of buf .

       val really_input : in_channel -> bytes -> int -> int -> unit

       really_input  ic  buf  pos len reads len characters from channel ic , storing them in byte sequence buf ,
       starting at character number pos .  Raise End_of_file if the end of file is reached before len characters
       have been read.  Raise Invalid_argument really_input if pos and len do not designate a valid range of buf
       .

       val really_input_string : in_channel -> int -> string

       really_input_string ic len reads len characters from channel ic and returns them in a new string.   Raise
       End_of_file if the end of file is reached before len characters have been read.

       Since 4.02.0

       val input_byte : in_channel -> 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.

       val input_binary_int : in_channel -> int

       Read an integer encoded in binary format  (4  bytes,  big-endian)  from  the  given  input  channel.  See
       output_binary_int .  Raise End_of_file if an end of file was reached while reading the integer.

       val input_value : in_channel -> 'a

       Read the representation of a structured value, as produced by output_value , and return the corresponding
       value.  This function is identical to Marshal.from_channel ; see the description of  module  Marshal  for
       more information, in particular concerning the lack of type safety.

       val seek_in : in_channel -> int -> 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.

       val pos_in : in_channel -> int

       Return the current reading position for the given channel.

       val in_channel_length : in_channel -> int

       Return the size (number of characters) of the regular file on which the given channel is opened.  If  the
       channel  is  opened  on  a file that is not a regular file, the result is meaningless.  The returned size
       does not take into account the end-of-line translations that can be performed when reading from a channel
       opened in text mode.

       val close_in : in_channel -> unit

       Close  the  given channel.  Input functions raise a Sys_error exception when they are applied to a closed
       input channel, except close_in , which does nothing when applied to an already closed channel.

       val close_in_noerr : in_channel -> unit

       Same as close_in , but ignore all errors.

       val set_binary_mode_in : in_channel -> bool -> unit

       set_binary_mode_in ic true sets the channel ic to binary mode: no translations take place  during  input.
       set_binary_mode_out  ic  false  sets the channel ic to text mode: depending on the operating system, some
       translations may take place during input.  For instance, under Windows, end-of-lines will  be  translated
       from  \r\n  to  \n .  This function has no effect under operating systems that do not distinguish between
       text mode and binary mode.

   Operations on large files
       module LargeFile : sig end

       Operations on large files.  This sub-module provides  64-bit  variants  of  the  channel  functions  that
       manipulate  file  positions and file sizes.  By representing positions and sizes by 64-bit integers (type
       int64 ) instead of regular integers (type int ), these alternate functions allow operating on files whose
       sizes are greater than max_int .

   References
       type 'a ref = {

       mutable contents : 'a ;
        }

       The type of references (mutable indirection cells) containing a value of type 'a .

       val ref : 'a -> 'a ref

       Return a fresh reference containing the given value.

       val (!)  : 'a ref -> 'a

       !r  returns  the  current contents of reference r .  Equivalent to fun r -> r.contents .  Unary operator,
       see Ocaml_operators for more information.

       val (:=) : 'a ref -> 'a -> unit

       r := a stores the value  of  a  in  reference  r  .   Equivalent  to  fun  r  v  ->  r.contents  <-  v  .
       Right-associative operator, see Ocaml_operators for more information.

       val incr : int ref -> unit

       Increment the integer contained in the given reference.  Equivalent to fun r -> r := succ !r .

       val decr : int ref -> unit

       Decrement the integer contained in the given reference.  Equivalent to fun r -> r := pred !r .

   Result type
       type ('a, 'b) result =
        | Ok of 'a
        | Error of 'b

       Since 4.03.0

   Operations on format strings
       Format  strings  are character strings with special lexical conventions that defines the functionality of
       formatted input/output functions. Format strings are used to read data  with  formatted  input  functions
       from module Scanf and to print data with formatted output functions from modules Printf and Format .

       Format strings are made of three kinds of entities:

       -conversions  specifications,  introduced by the special character '%' followed by one or more characters
       specifying what kind of argument to read or print,

       -formatting indications, introduced by the special character '@'  followed  by  one  or  more  characters
       specifying how to read or print the argument,

       -plain  characters  that  are regular characters with usual lexical conventions. Plain characters specify
       string literals to be read in the input or printed in the output.

       There is an additional lexical rule to escape the special characters '%' and '@' in format strings: if  a
       special  character  follows  a  '%'  character, it is treated as a plain character. In other words, %% is
       considered as a plain '%' and %@ as a plain '@' .

       For more information about conversion specifications  and  formatting  indications  available,  read  the
       documentation of modules Scanf , Printf and Format .

       Format  strings  have  a  general and highly polymorphic type ('a, 'b, 'c, 'd, 'e, 'f) format6 .  The two
       simplified types, format and format4 below are included for backward compatibility with earlier  releases
       of OCaml.

       The meaning of format string type parameters is as follows:

       -  'a  is  the  type  of  the  parameters  of  the  format for formatted output functions ( printf -style
       functions); 'a is the type of the values read by the format for formatted input functions ( scanf  -style
       functions).

       -  'b  is  the  type  of  input  source  for  formatted input functions and the type of output target for
       formatted output functions.  For printf -style functions from module Printf , 'b is typically out_channel
       ;  for  printf  -style functions from module Format , 'b is typically Format.formatter ; for scanf -style
       functions from module Scanf , 'b is typically Scanf.Scanning.in_channel .

       Type argument 'b is also the type of the first argument given to user's defined printing functions for %a
       and %t conversions, and user's defined reading functions for %r conversion.

       -  'c  is  the  type of the result of the %a and %t printing functions, and also the type of the argument
       transmitted to the first argument of kprintf -style functions or to the kscanf -style functions.

       - 'd is the type of parameters for the scanf -style functions.

       - 'e is the type of the receiver function for the scanf -style functions.

       - 'f is the final result type of a formatted input/output function  invocation:  for  the  printf  -style
       functions,  it is typically unit ; for the scanf -style functions, it is typically the result type of the
       receiver function.

       type ('a, 'b, 'c, 'd, 'e, 'f) format6 = ('a, 'b, 'c, 'd, 'e, 'f) CamlinternalFormatBasics.format6

       type ('a, 'b, 'c, 'd) format4 = ('a, 'b, 'c, 'c, 'c, 'd) format6

       type ('a, 'b, 'c) format = ('a, 'b, 'c, 'c) format4

       val string_of_format : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> string

       Converts a format string into a string.

       val format_of_string : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> ('a, 'b, 'c, 'd, 'e, 'f) format6

       format_of_string s returns a format string read from the string literal s .  Note:  format_of_string  can
       not convert a string argument that is not a literal. If you need this functionality, use the more general
       Scanf.format_from_string function.

       val (^^) : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> ('f, 'b, 'c, 'e, 'g, 'h) format6 -> ('a, 'b, 'c,  'd,  'g,
       'h) format6

       f1  ^^  f2  catenates  format  strings  f1  and  f2  .  The result is a format string that behaves as the
       concatenation of format strings f1 and f2 : in case of formatted output, it accepts arguments from  f1  ,
       then  arguments from f2 ; in case of formatted input, it returns results from f1 , then results from f2 .
       Right-associative operator, see Ocaml_operators for more information.

   Program termination
       val exit : int -> 'a

       Terminate the process, returning the given status code to the operating system: usually 0 to indicate  no
       errors,  and  a  small  positive  integer to indicate failure.  All open output channels are flushed with
       flush_all .  An implicit exit 0 is performed each time a program terminates normally.  An implicit exit 2
       is performed if the program terminates early because of an uncaught exception.

       val at_exit : (unit -> unit) -> unit

       Register  the  given  function  to  be  called at program termination time. The functions registered with
       at_exit will be called when the program does any of the following:

       -executes exit

       -terminates, either normally or because of an uncaught exception

       -executes the C function caml_shutdown .  The functions are called in 'last in,  first  out'  order:  the
       function most recently added with at_exit is called first.

   Standard library modules
       module Arg : (module Stdlib__arg)

       module Array : (module Stdlib__array)

       module ArrayLabels : (module Stdlib__arrayLabels)

       module Bigarray : (module Stdlib__bigarray)

       module Bool : (module Stdlib__bool)

       module Buffer : (module Stdlib__buffer)

       module Bytes : (module Stdlib__bytes)

       module BytesLabels : (module Stdlib__bytesLabels)

       module Callback : (module Stdlib__callback)

       module Char : (module Stdlib__char)

       module Complex : (module Stdlib__complex)

       module Digest : (module Stdlib__digest)

       module Ephemeron : (module Stdlib__ephemeron)

       module Filename : (module Stdlib__filename)

       module Float : (module Stdlib__float)

       module Format : (module Stdlib__format)

       module Fun : (module Stdlib__fun)

       module Gc : (module Stdlib__gc)

       module Genlex : (module Stdlib__genlex)

       module Hashtbl : (module Stdlib__hashtbl)

       module Int : (module Stdlib__int)

       module Int32 : (module Stdlib__int32)

       module Int64 : (module Stdlib__int64)

       module Lazy : (module Stdlib__lazy)

       module Lexing : (module Stdlib__lexing)

       module List : (module Stdlib__list)

       module ListLabels : (module Stdlib__listLabels)

       module Map : (module Stdlib__map)

       module Marshal : (module Stdlib__marshal)

       module MoreLabels : (module Stdlib__moreLabels)

       module Nativeint : (module Stdlib__nativeint)

       module Obj : (module Stdlib__obj)

       module Oo : (module Stdlib__oo)

       module Option : (module Stdlib__option)

       module Parsing : (module Stdlib__parsing)

       module Pervasives : (module Stdlib__pervasives)

       module Printexc : (module Stdlib__printexc)

       module Printf : (module Stdlib__printf)

       module Queue : (module Stdlib__queue)

       module Random : (module Stdlib__random)

       module Result : (module Stdlib__result)

       module Scanf : (module Stdlib__scanf)

       module Seq : (module Stdlib__seq)

       module Set : (module Stdlib__set)

       module Spacetime : (module Stdlib__spacetime)

       module Stack : (module Stdlib__stack)

       module StdLabels : (module Stdlib__stdLabels)

       module Stream : (module Stdlib__stream)

       module String : (module Stdlib__string)

       module StringLabels : (module Stdlib__stringLabels)

       module Sys : (module Stdlib__sys)

       module Uchar : (module Stdlib__uchar)

       module Unit : (module Stdlib__unit)

       module Weak : (module Stdlib__weak)