package prelude
Library
Module
Module type
Parameter
Class
Class type
include module type of struct include Stdlib end
Exceptions
The Exit
exception is not raised by any library function. It is provided for use in your programs.
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 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 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 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 raised by the garbage collector when there is insufficient memory to complete the computation. (Not reliable for allocations on the minor heap.)
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.
Before 4.10, it was not fully implemented by the native-code compiler.
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 raised by input functions to signal that the end of file has been reached.
Exception raised by integer division and remainder operations when their second argument is zero.
A special case of Sys_error raised when no I/O is possible on a non-blocking I/O channel.
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
Boolean operations
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.
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.
Debugging
__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".
__LINE__
returns the line number at which this expression appears in the file currently being parsed by the compiler.
__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.
__FUNCTION__
returns the name of the current function or method, including any enclosing modules or classes.
__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".
__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.
__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.
Composition operators
Reverse-application operator: x |> f |> g
is exactly equivalent to g (f (x))
. Left-associative operator, see Ocaml_operators
for more information.
Application operator: g @@ f @@ x
is exactly equivalent to g (f (x))
. Right-associative operator, see Ocaml_operators
for more information.
Integer arithmetic
Integers are Sys.int_size
bits wide. All operations are taken modulo 2Sys.int_size
. They do not fail on overflow.
Unary negation. You can also write - e
instead of ~- e
. Unary operator, see Ocaml_operators
for more information.
Unary addition. You can also write + e
instead of ~+ e
. Unary operator, see Ocaml_operators
for more information.
Integer addition. Left-associative operator, see Ocaml_operators
for more information.
Integer subtraction. Left-associative operator, , see Ocaml_operators
for more information.
Integer multiplication. Left-associative operator, see Ocaml_operators
for more information.
Integer division. 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.
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
. Left-associative operator, see Ocaml_operators
for more information.
abs x
is the absolute value of x
. On min_int
this is min_int
itself and thus remains negative.
Bitwise operations
Bitwise logical and. Left-associative operator, see Ocaml_operators
for more information.
Bitwise logical or. Left-associative operator, see Ocaml_operators
for more information.
Bitwise logical exclusive or. Left-associative operator, see Ocaml_operators
for more information.
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.
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.
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
, basic arithmetic operations (+.
, -.
, *.
, /.
) with nan
as an argument return nan
, ...
Unary negation. You can also write -. e
instead of ~-. e
. Unary operator, see Ocaml_operators
for more information.
Unary addition. You can also write +. e
instead of ~+. e
. Unary operator, see Ocaml_operators
for more information.
Floating-point addition. Left-associative operator, see Ocaml_operators
for more information.
Floating-point subtraction. Left-associative operator, see Ocaml_operators
for more information.
Floating-point multiplication. Left-associative operator, see Ocaml_operators
for more information.
Floating-point division. Left-associative operator, see Ocaml_operators
for more information.
Exponentiation. Right-associative operator, see Ocaml_operators
for more information.
expm1 x
computes exp x -. 1.0
, giving numerically-accurate results even if x
is close to 0.0
.
log1p x
computes log(1.0 +. x)
(natural logarithm), giving numerically-accurate results even if x
is close to 0.0
.
Arc cosine. The argument must fall within the range [-1.0, 1.0]
. Result is in radians and is between 0.0
and pi
.
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
.
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
.
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
.
Hyperbolic arc cosine. The argument must fall within the range [1.0, inf]
. Result is in radians and is between 0.0
and inf
.
Hyperbolic arc sine. The argument and result range over the entire real line. Result is in radians.
Hyperbolic arc tangent. The argument must fall within the range [-1.0, 1.0]
. Result is in radians and ranges over the entire real line.
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.
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.
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.
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.
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
.
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.
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, unless otherwise specified in IEEE 754 standard. As for floating-point comparisons, =
, <
, <=
, >
and >=
return false
and <>
returns true
if one or both of their arguments is nan
.
nan
is a quiet NaN since 5.1; it was a signaling NaN before.
The difference between 1.0
and the smallest exactly representable floating-point number greater than 1.0
.
type fpclass = fpclass =
The five classes of floating-point numbers, as determined by the Stdlib.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
.
Character operations
More character operations are provided in module Char
.
Unit operations
String conversion functions
Return the string representation of a boolean. As the returned values may be shared, the user should not modify them directly.
Return a string representation of a floating-point number.
This conversion can involve a loss of precision. For greater control over the manner in which the number is printed, see Printf
.
Pair operations
List operations
More list operations are provided in module List
.
l0 @ l1
appends l1
to l0
. Same function as List.append
. 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 = in_channel
The type of input channel.
type out_channel = 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
Output functions on standard error
Input functions on standard input
General output functions
type open_flag = 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 Stdlib.open_out_gen
and Stdlib.open_in_gen
.
General input functions
val pos_in : in_channel -> int
Return the current reading position for the given channel. For files opened in text mode under Windows, the returned position is approximate (owing to end-of-line conversion); in particular, saving the current position with pos_in
, then going back to this position using seek_in
will not work. For this programming idiom to work reliably and portably, the file must be opened in binary mode.
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 = LargeFile
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
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
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. Forprintf
-style functions from modulePrintf
,'b
is typicallyout_channel
; forprintf
-style functions from moduleFormat
,'b
is typicallyFormat.formatter
; forscanf
-style functions from moduleScanf
,'b
is typicallyScanf.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 ofkprintf
-style functions or to thekscanf
-style functions.
'd
is the type of parameters for thescanf
-style functions.
'e
is the type of the receiver function for thescanf
-style functions.
'f
is the final result type of a formatted input/output function invocation: for theprintf
-style functions, it is typicallyunit
; for thescanf
-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.
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
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
. The callbacks registered with Domain.at_exit
are called followed by those registered with Stdlib.at_exit
.
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.
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
Stdlib.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 withat_exit
is called first.
Standard library modules
module Array = Array
module Atomic = Atomic
module Bigarray = Bigarray
module Bool = Bool
module Buffer = Buffer
module Bytes = Bytes
module Callback = Callback
module Char = Char
module Complex = Complex
module Condition = Condition
module Digest = Digest
module Domain = Domain
module Effect = Effect
module Either = Either
module Ephemeron = Ephemeron
module Fun = Fun
module Gc = Gc
module Hashtbl = Hashtbl
module In_channel = In_channel
module Int = Int
module Lazy = Lazy
module Lexing = Lexing
module List = List
module Map = Map
module Marshal = Marshal
module Mutex = Mutex
module Nativeint = Nativeint
module Obj = Obj
module Oo = Oo
module Option = Option
module Out_channel = Out_channel
module Printexc = Printexc
module Queue = Queue
module Random = Random
module Result = Result
module Scanf = Scanf
module Semaphore = Semaphore
module Seq = Seq
module Set = Set
module Stack = Stack
module String = String
module Type = Type
module Uchar = Uchar
module Unit = Unit
module Weak = Weak
module Empty : sig ... end
module Float : sig ... end
module Int32 : sig ... end
module Int64 : sig ... end
module Printf = Empty
module Fmt : sig ... end
module Format = Empty
module Arg = Empty
module Cmdliner = Cmdliner
module ArrayLabels = Empty
module BytesLabels = Empty
module ListLabels = Empty
module MoreLabels = Empty
module StdLabels = Empty
module StringLabels = Empty
module Filename = Empty
module Parsing = Empty
module Stdlib = Empty
module Sys : sig ... end