module Pervasives: sig end
This module provides the basic operations over the builtin types (numbers, booleans, strings, exceptions, references, lists, arrays, inputoutput channels, ...)
This module is automatically opened at the beginning of each compilation.
All components of this module can therefore be referred by their short
name, without prefixing them by Pervasives
.
Exceptions

val raise : exn > 'a
val invalid_arg : string > 'a
Invalid_argument
with the given string.val failwith : string > 'a
Failure
with the given string.exception Exit
Exit
exception is not raised by any library function. It is
provided for use in your programs.
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 may raise Invalid_argument
.
Equality between cyclic data structures may not terminate.val (<>) : 'a > 'a > bool
Pervasives.(=)
.val (<) : 'a > 'a > bool
Pervasives.(>=)
.val (>) : 'a > 'a > bool
Pervasives.(>=)
.val (<=) : 'a > 'a > bool
Pervasives.(>=)
.val (>=) : 'a > 'a > bool
(=)
. As in the case
of (=)
, mutable structures are compared by contents.
Comparison between functional values may raise Invalid_argument
.
Comparison between cyclic structures may not terminate.val compare : 'a > 'a > int
compare x y
returns 0
if x=y
, a negative integer if
x<y
, and a positive integer if x>y
. The same restrictions
as for =
apply. compare
can be used as the comparison function
required by the Set.Make
and Map.Make
functors.val min : 'a > 'a > 'a
val max : 'a > 'a > 'a
val (==) : 'a > 'a > bool
e1 == e2
tests for physical equality of e1
and e2
.
On integers and characters, physical equality is identical to structural
equality. On mutable structures, e1 == e2
is true if and only if
physical modification of e1
also affects e2
.
On nonmutable structures, the behavior of (==)
is
implementationdependent; however, it is guaranteed that
e1 == e2
implies e1 = e2
.val (!=) : 'a > 'a > bool
Pervasives.(==)
.
Boolean operations

val not : bool > bool
val (&&) : bool > bool > bool
e1 && e2
, e1
is evaluated first, and if it returns false
,
e2
is not evaluated at all.val (&) : bool > bool > bool
val () : bool > bool > bool
e1  e2
, e1
is evaluated first, and if it returns true
,
e2
is not evaluated at all.val or : bool > bool > bool
Integer arithmetic

val (~) : int > int
e
instead of ~e
.val succ : int > int
succ x
is x+1
.val pred : int > int
pred x
is x1
.val (+) : int > int > int
val () : int > int > int
val (*) : int > int > int
val (/) : int > int > int
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)
.val mod : int > int > int
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
.
Notice that x mod y
is negative if and only if x < 0
.val abs : int > int
val max_int : int
val min_int : int
Bitwise operations

val land : int > int > int
val lor : int > int > int
val lxor : int > int > int
val lnot : int > int
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 >= bitsize
,
where bitsize
is 32
on a 32bit platform and
64
on a 64bit platform.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 >= bitsize
.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 >= bitsize
.
Floatingpoint arithmetic

Caml's floatingpoint numbers follow the
IEEE 754 standard, using double precision (64 bits) numbers.
Floatingpoint 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
floatingpoint computations as expected: for instance,
1.0 /. infinity
is 0.0
, and any operation with nan
as
argument returns nan
as result.
val (~.) : float > float
.e
instead of ~.e
.val (+.) : float > float > float
val (.) : float > float > float
val (*.) : float > float > float
val (/.) : float > float > float
val (**) : float > float > float
val sqrt : float > float
val exp : float > float
val log : float > float
val log10 : float > float
val cos : float > float
Pervasives.atan2
.val sin : float > float
Pervasives.atan2
.val tan : float > float
Pervasives.atan2
.val acos : float > float
Pervasives.atan2
.val asin : float > float
Pervasives.atan2
.val atan : float > float
Pervasives.atan2
.val atan2 : float > float > float
val cosh : float > float
Pervasives.tanh
.val sinh : float > float
Pervasives.tanh
.val tanh : float > float
val ceil : float > float
Pervasives.floor
.val floor : float > float
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
.val abs_float : float > float
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 nonzero, 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
Pervasives.float_of_int
.val float_of_int : int > float
val truncate : float > int
Pervasives.int_of_float
.val int_of_float : float > int
val infinity : float
val neg_infinity : float
val nan : float
0.0 /. 0.0
. Stands for
``not a number''.val max_float : float
float
.val min_float : float
float
.val epsilon_float : float
x
such that 1.0 +. x <> 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  *) 
Pervasives.classify_float
function.val classify_float : float > fpclass
String operations

More string operations are provided in module String
.
val (^) : string > string > string
Character operations

More character operations are provided in module Char
.
val int_of_char : char > int
val char_of_int : int > char
Invalid_argument "char_of_int"
if the argument is
outside the range 0255.
Unit operations

val ignore : 'a > unit
()
.
For instance, ignore(f x)
discards the result of
the sideeffecting 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
val bool_of_string : string > bool
Invalid_argument "bool_of_string"
if the string is not
"true"
or "false"
.val string_of_int : int > string
val int_of_string : string > int
0x
or 0X
), octal (if it begins with 0o
or 0O
),
or binary (if it begins with 0b
or 0B
).
Raise Failure "int_of_string"
if the given string is not
a valid representation of an integer.val string_of_float : float > string
val float_of_string : string > float
Failure "float_of_string"
if the given string is not a valid representation of a float.
Pair operations

val fst : 'a * 'b > 'a
val snd : 'a * 'b > 'b
List operations

More list operations are provided in module List
.
val (@) : 'a list > 'a list > 'a list
Input/output

type
in_channel
type
out_channel
val stdin : in_channel
val stdout : out_channel
val stderr : out_channel
Output functions on standard output

val print_char : char > unit
val print_string : string > unit
val print_int : int > unit
val print_float : float > unit
val print_endline : string > unit
val print_newline : unit > unit
Output functions on standard error

val prerr_char : char > unit
val prerr_string : string > unit
val prerr_int : int > unit
val prerr_float : float > unit
val prerr_endline : string > unit
val prerr_newline : unit > unit
Input functions on standard input

val read_line : unit > string
val read_int : unit > int
Failure "int_of_string"
if the line read is not a valid representation of an integer.val read_float : unit > float
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 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 nonblocking mode.  *) 
val open_out : string > out_channel
Sys_error
if the file could not be opened.val open_out_bin : string > out_channel
Pervasives.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 Pervasives.open_out
.val open_out_gen : open_flag list > int > string > out_channel
mode
specify the opening mode. The extra argument perm
specifies
the file permissions, in case the file must be created.
Pervasives.open_out
and Pervasives.open_out_bin
are special
cases of this function.val flush : out_channel > unit
val flush_all : unit > unit
val output_char : out_channel > char > unit
val output_string : out_channel > string > unit
val output : out_channel > string > int > int > unit
output oc buf pos len
writes len
characters from string buf
,
starting at offset pos
, to the given output channel oc
.
Raise Invalid_argument "output"
if pos
and len
do not
designate a valid substring of buf
.val output_byte : out_channel > int > unit
val output_binary_int : out_channel > int > unit
Pervasives.input_binary_int
function. The format is compatible across
all machines for a given version of Objective Caml.val output_value : out_channel > 'a > unit
Pervasives.input_value
. See the description of module
Marshal
for more information. Pervasives.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
val out_channel_length : out_channel > int
val close_out : out_channel > unit
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
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,
endoflines 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
Sys_error
if the file could not be opened.val open_in_bin : string > in_channel
Pervasives.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 Pervasives.open_in
.val open_in_gen : open_flag list > int > string > in_channel
mode
and perm
specify the opening mode and file permissions.
Pervasives.open_in
and Pervasives.open_in_bin
are special
cases of this function.val input_char : in_channel > char
End_of_file
if there are no more characters to read.val input_line : in_channel > string
End_of_file
if the end of the file is reached
at the beginning of line.val input : in_channel > string > int > int > int
input ic buf pos len
reads up to len
characters from
the given channel ic
, storing them in string buf
, starting at
character number pos
.
It returns the actual number of characters read, between 0 and
len
(inclusive).
A return value of 0 means that the end of file was reached.
A return value between 0 and len
exclusive means that
not all requested len
characters were read, either because
no more characters were available at that time, or because
the implementation found it convenient to do a partial read;
input
must be called again to read the remaining characters,
if desired. (See also Pervasives.really_input
for reading
exactly len
characters.)
Exception Invalid_argument "input"
is raised if pos
and len
do not designate a valid substring of buf
.val really_input : in_channel > string > int > int > unit
really_input ic buf pos len
reads len
characters from channel ic
,
storing them in string buf
, starting at character number pos
.
Raise End_of_file
if the end of file is reached before len
characters have been read.
Raise Invalid_argument "really_input"
if
pos
and len
do not designate a valid substring of buf
.val input_byte : in_channel > int
Pervasives.input_char
, but return the 8bit integer representing
the character.
Raise End_of_file
if an end of file was reached.val input_binary_int : in_channel > int
Pervasives.output_binary_int
.
Raise End_of_file
if an end of file was reached while reading the
integer.val input_value : in_channel > 'a
Pervasives.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
val in_channel_length : in_channel > int
val close_in : in_channel > unit
Sys_error
exception when they are applied to a closed input channel,
except close_in
, which does nothing when applied to an already
closed channel. Note that close_in
may raise Sys_error
if
the operating system signals an error.val close_in_noerr : in_channel > unit
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,
endoflines 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
References

type 'a
ref = {

mutable contents : 
'a
.val ref : 'a > 'a ref
val (!) : 'a ref > 'a
!r
returns the current contents of reference r
.
Equivalent to fun r > r.contents
.val (:=) : 'a ref > 'a > unit
r := a
stores the value of a
in reference r
.
Equivalent to fun r v > r.contents < v
.val incr : int ref > unit
fun r > r := succ !r
.val decr : int ref > unit
fun r > r := pred !r
.
Operations on format strings

Printf
and Scanf
for more operations on
format strings.type('a, 'b, 'c)
format =('a, 'b, 'c, 'c) format4
'a
is the type of the parameters of the format,
'c
is the result type for the "printf"style function,
and 'b
is the type of the first argument given to
%a
and %t
printing functions.val string_of_format : ('a, 'b, 'c, 'd) format4 > string
val format_of_string : ('a, 'b, 'c, 'd) format4 > ('a, 'b, 'c, 'd) format4
format_of_string s
returns a format string read from the string
literal s
.val (^^) : ('a, 'b, 'c, 'd) format4 >
('d, 'b, 'c, 'e) format4 > ('a, 'b, 'c, 'e) format4
f1 ^^ f2
catenates formats f1
and f2
. The result is a format
that accepts arguments from f1
, then arguments from f2
.
Program termination

val exit : int > 'a
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
at_exit
will be called when the program executes Pervasives.exit
,
or terminates, either normally or because of an uncaught exception.
The functions are called in ``last in, first out'' order:
the function most recently added with at_exit
is called first.