
Module Pervasivesmodule Pervasives:
The initially opened module.
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
val raise :
Raise the given exception value
val invalid_arg :
Raise exception
Invalid_argument with the given string.val failwith :
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.
val (=) : 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 (<>) :
Negation of
Pervasives.(=) .val (<) :
See
Pervasives.(>=) .val (>) :
See
Pervasives.(>=) .val (<=) :
See
Pervasives.(>=) .val (>=) :
Structural ordering functions. These functions coincide with
the usual orderings over integers, characters, strings
and floatingpoint 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 may raise Invalid_argument .
Comparison between cyclic structures may not terminate.val compare : 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 :
Return the smaller of the two arguments.
val max :
Return the greater of the two arguments.
val (==) : 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 (!=) :
Negation of
Pervasives.(==) .
val not :
The boolean negation.
val (&&) :
The boolean ``and''. Evaluation is sequential, lefttoright:
in
e1 && e2 , e1 is evaluated first, and if it returns false ,
e2 is not evaluated at all.val (&) :
val () :
The boolean ``or''. Evaluation is sequential, lefttoright:
in
e1  e2 , e1 is evaluated first, and if it returns true ,
e2 is not evaluated at all.val or :
Integers are 31 bits wide (or 63 bits on 64bit processors). All operations are taken modulo 2^{31} (or 2^{63}). They do not fail on overflow. val (~) :
Unary negation. You can also write
e instead of ~e .val succ : succ x is x+1 .val pred : pred x is x1 .val (+) :
Integer addition.
val () :
Integer subtraction.
val (*) :
Integer multiplication.
val (/) :
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) .val mod :
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) .
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 :
Return the absolute value of the argument.
val max_int :
The greatest representable integer.
val min_int :
The smallest representable integer.
val land :
Bitwise logical and.
val lor :
Bitwise logical or.
val lxor :
Bitwise logical exclusive or.
val lnot :
Bitwise logical negation.
val lsl : 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 : 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 : 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 .
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 val (~.) :
Unary negation. You can also write
.e instead of ~.e .val (+.) :
Floatingpoint addition
val (.) :
Floatingpoint subtraction
val (*.) :
Floatingpoint multiplication
val (/.) :
Floatingpoint division.
val (**) :
Exponentiation
val sqrt :
Square root
val exp :
Exponential.
val log :
Natural logarithm.
val log10 :
Base 10 logarithm.
val cos :
See
Pervasives.atan2 .val sin :
See
Pervasives.atan2 .val tan :
See
Pervasives.atan2 .val acos :
See
Pervasives.atan2 .val asin :
See
Pervasives.atan2 .val atan :
See
Pervasives.atan2 .val atan2 :
The usual trigonometric functions.
val cosh :
See
Pervasives.tanh .val sinh :
See
Pervasives.tanh .val tanh :
The usual hyperbolic trigonometric functions.
val ceil :
See
Pervasives.floor .val floor :
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 .val abs_float :
Return the absolute value of the argument.
val mod_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 : 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 : ldexp x n returns x *. 2 ** n .val modf : modf f returns the pair of the fractional and integral
part of f .val float :
Same as
Pervasives.float_of_int .val float_of_int :
Convert an integer to floatingpoint.
val truncate :
Same as
Pervasives.int_of_float .val int_of_float :
Truncate the given floatingpoint number to an integer.
The result is unspecified if it falls outside the
range of representable integers.
val infinity :
Positive infinity.
val neg_infinity :
Negative infinity.
val nan :
A special floatingpoint value denoting the result of an
undefined operation such as
0.0 /. 0.0 . Stands for
``not a number''.val max_float :
The largest positive finite value of type
float .val min_float :
The smallest positive, nonzero, nondenormalized value of type
float .val epsilon_float :
The smallest positive float
x such that 1.0 +. x <> 1.0 .type fpclass =
The five classes of floatingpoint numbers, as determined by
the
Pervasives.classify_float function.val classify_float :
Return the class of the given floatingpoint number:
normal, subnormal, zero, infinite, or not a number.
More string operations are provided in module val (^) :
String concatenation.
More character operations are provided in module val int_of_char :
Return the ASCII code of the argument.
val char_of_int :
Return the character with the given ASCII code.
Raise
Invalid_argument "char_of_int" if the argument is
outside the range 0255.
val ignore :
Discard the value of its argument and return
() .
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.
val string_of_bool :
Return the string representation of a boolean.
val bool_of_string :
Convert the given string to a boolean.
Raise
Invalid_argument "bool_of_string" if the string is not
"true" or "false" .val string_of_int :
Return the string representation of an integer, in decimal.
val int_of_string :
Convert the given string to an integer.
The string is read in decimal (by default) or in hexadecimal,
octal or binary if the string begins with
0x , 0o or 0b
respectively.
Raise Failure "int_of_string" if the given string is not
a valid representation of an integer.val string_of_float :
Return the string representation of a floatingpoint number.
val float_of_string :
Convert the given string to a float. Raise
Failure "float_of_string"
if the given string is not a valid representation of a float.
val fst :
Return the first component of a pair.
val snd :
Return the second component of a pair.
More list operations are provided in module val (@) :
List concatenation.
type in_channel
The type of input channel.
type out_channel
The type of output channel.
val stdin :
The standard input for the process.
val stdout :
The standard output for the process.
val stderr :
The standard error ouput for the process.
val print_char :
Print a character on standard output.
val print_string :
Print a string on standard output.
val print_int :
Print an integer, in decimal, on standard output.
val print_float :
Print a floatingpoint number, in decimal, on standard output.
val print_endline :
Print a string, followed by a newline character, on
standard output.
val print_newline :
Print a newline character on standard output, and flush
standard output. This can be used to simulate line
buffering of standard output.
val prerr_char :
Print a character on standard error.
val prerr_string :
Print a string on standard error.
val prerr_int :
Print an integer, in decimal, on standard error.
val prerr_float :
Print a floatingpoint number, in decimal, on standard error.
val prerr_endline :
Print a string, followed by a newline character on standard error
and flush standard error.
val prerr_newline :
Print a newline character on standard error, and flush
standard error.
val read_line :
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 :
Flush standard output, then read one line from standard input
and convert it to an integer. Raise
Failure "int_of_string"
if the line read is not a valid representation of an integer.val read_float :
Flush standard output, then read one line from standard input
and convert it to a floatingpoint number.
The result is unspecified if the line read is not a valid
representation of a floatingpoint number.
type open_flag =
val open_out :
Open the named file for writing, and return a new output channel
on that file, positionned at the beginning of the file. The
file is truncated to zero length if it already exists. It
is created if it does not already exists.
Raise
Sys_error if the file could not be opened.val open_out_bin :
Same as
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 the named file for writing, as above. The extra argument
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 :
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 :
Flush all opened output channels.
val output_char :
Write the character on the given output channel.
val output_string :
Write the string on the given output channel.
val output : 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 :
Write one 8bit integer (as the single character with that code)
on the given output channel. The given integer is taken modulo
256.
val output_binary_int :
Write one integer in binary format on the given output channel.
The only reliable way to read it back is through the
Pervasives.input_binary_int function. The format is compatible across
all machines for a given version of Objective Caml.val output_value :
Write the representation of a structured value of any type
to a channel. Circularities and sharing inside the value
are detected and preserved. The object can be read back,
by the function
Pervasives.input_value . 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 : 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 :
Return the current writing position for the given channel.
val out_channel_length :
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.
val close_out :
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.val set_binary_mode_out : 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.
val open_in :
Open the named file for reading, and return a new input channel
on that file, positionned at the beginning of the file.
Raise
Sys_error if the file could not be opened.val open_in_bin :
Same as
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 the named file for reading, as above. The extra arguments
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 :
Read one character from the given input channel.
Raise
End_of_file if there are no more characters to read.val input_line :
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 : 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 : 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 :
Same as
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 :
Read an integer encoded in binary format from the given input
channel. See
Pervasives.output_binary_int .
Raise End_of_file if an end of file was reached while reading the
integer.val input_value :
Read the representation of a structured value, as produced
by
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 : 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 :
Return the current reading position for the given channel.
val in_channel_length :
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.
val close_in :
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 set_binary_mode_in : 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.
module LargeFile:
Operations on large files.
type
The type of references (mutable indirection cells) containing
a value of type
'a .val ref :
Return a fresh reference containing the given value.
val (!) : !r returns the current contents of reference r .
Equivalent to fun r > r.contents .val (:=) : r := a stores the value of a in reference r .
Equivalent to fun r v > r.contents < v .val incr :
Increment the integer contained in the given reference.
Equivalent to
fun r > r := succ !r .val decr :
Decrement the integer contained in the given reference.
Equivalent to
fun r > r := pred !r .
val exit :
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 opened output channels are flushed.
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 :
Register the given function to be called at program
termination time. The functions registered with
at_exit
will be called when the program executes Pervasives.exit ,
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. 