include module type of struct include Std end
Std_kernel
defines modules exposed by Core_kernel
that are not overridden by Core
. It is used in core.ml
to re-export these modules.
Exceptions
Raise the given exception value
val raise_notrace : exn -> 'a
A faster version raise
which does not record the backtrace.
val invalid_arg : string -> 'a
Raise exception Invalid_argument
with the given string.
val failwith : string -> 'a
Raise exception Failure
with the given string.
The 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 raises Invalid_argument
. Equality between cyclic data structures may not terminate.
val (<>) : 'a -> 'a -> bool
Negation of Pervasives.(=)
.
val (<) : 'a -> 'a -> bool
val (>) : 'a -> 'a -> bool
val (<=) : 'a -> 'a -> bool
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.
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 Pervasives.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.
Return the smaller of the two arguments. The result is unspecified if one of the arguments contains the float value nan
.
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
.
val (!=) : 'a -> 'a -> bool
Negation of Pervasives.(==)
.
Boolean operations
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.
val (&) : bool -> bool -> bool
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.
val or : bool -> bool -> bool
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"
__FILE__
returns the name of the file currently being parsed by the compiler.
__LINE__
returns the line number at which this expression appears in the file currently being parsed by the compiler.
__MODULE__
returns the module name of the file being parsed by the compiler.
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.
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"
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.
val __POS_OF__ : 'a -> (string * int * int * int) * 'a
__POS_OF__ expr
returns a pair (expr,loc)
, 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
val (|>) : 'a -> ('a -> 'b) -> 'b
Reverse-application operator: x |> f |> g
is exactly equivalent to g (f (x))
.
val (@@) : ('a -> 'b) -> 'a -> 'b
Application operator: g @@ f @@ x
is exactly equivalent to g (f (x))
.
Integer arithmetic
Integers are 31 bits wide (or 63 bits on 64-bit processors). All operations are taken modulo 231 (or 263). They do not fail on overflow.
Unary negation. You can also write - e
instead of ~- e
.
Unary addition. You can also write + e
instead of ~+ e
.
val (+) : int -> int -> int
val (-) : int -> int -> int
val (*) : int -> int -> int
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)
.
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.
Return the absolute value of the argument. Note that this may be negative if the argument is min_int
.
The greatest representable integer.
The smallest representable integer.
Bitwise operations
val (land) : int -> int -> int
val (lor) : int -> int -> int
val (lxor) : int -> int -> int
Bitwise logical exclusive or.
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 >= bitsize
, where bitsize
is 32
on a 32-bit platform and 64
on a 64-bit 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
.
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
.
val (~+.) : float -> float
Unary addition. You can also write +. e
instead of ~+. e
.
val (+.) : float -> float -> float
val (-.) : float -> float -> float
Floating-point subtraction
val (*.) : float -> float -> float
Floating-point multiplication
val (/.) : float -> float -> float
val (**) : float -> float -> float
val sqrt : float -> float
val log10 : float -> float
val expm1 : float -> float
expm1 x
computes exp x -. 1.0
, giving numerically-accurate results even if x
is close to 0.0
.
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
.
Cosine. Argument is in radians.
Sine. Argument is in radians.
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.
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.
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
.
Same as Pervasives.float_of_int
.
val float_of_int : int -> float
Convert an integer to floating-point.
val truncate : float -> int
Same as Pervasives.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.
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
.
The largest positive finite value of type 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 = Pervasives.fpclass =
| FP_normal
Normal number, none of the below
| FP_subnormal
Number very close to 0.0, has reduced precision
| FP_zero
| 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 Pervasives.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
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
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 : string -> bool
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 : int -> string
Return the string representation of an integer, in decimal.
val int_of_string : string -> int
Convert the given string to an integer. The string is read in decimal (by default) or in hexadecimal (if it begins with 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, or if the integer represented exceeds the range of integers representable in type int
.
val string_of_float : float -> string
Return the string representation of a floating-point number.
val float_of_string : string -> float
Convert the given string to a float. Raise Failure "float_of_string"
if the given string is not a valid representation of a float.
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
.
Note: all input/output functions can raise Sys_error
when the system calls they invoke fail.
type in_channel = Pervasives.in_channel
The type of input channel.
type out_channel = Pervasives.out_channel
The type of output channel.
val stdin : Pervasives.in_channel
The standard input for the process.
val stdout : Pervasives.out_channel
The standard output for the process.
val stderr : Pervasives.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.
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.
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.
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 : unit -> 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 : unit -> float
Flush standard output, then read one line from standard input and convert it to a floating-point number. The result is unspecified if the line read is not a valid representation of a floating-point number.
General output functions
type open_flag = Pervasives.open_flag =
| Open_rdonly
| Open_wronly
| 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 Pervasives.open_out_gen
and Pervasives.open_in_gen
.
val open_out : string -> Pervasives.out_channel
Open the named file for writing, and return a new output channel on that file, positionned at the beginning of the file. The file is truncated to zero length if it already exists. It is created if it does not already exists.
val open_out_bin : string -> Pervasives.out_channel
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 :
Pervasives.open_flag list ->
int ->
string ->
Pervasives.out_channel
open_out_gen mode perm filename
opens the named file for writing, as described 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 : Pervasives.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 : Pervasives.out_channel -> char -> unit
Write the character on the given output channel.
val output_string : Pervasives.out_channel -> string -> unit
Write the string on the given output channel.
val output_bytes : Pervasives.out_channel -> bytes -> unit
Write the byte sequence on the given output channel.
val output : Pervasives.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 : Pervasives.out_channel -> string -> int -> int -> unit
Same as output
but take a string as argument instead of a byte sequence.
val output_byte : Pervasives.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 : Pervasives.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 232. 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 OCaml.
val output_value : Pervasives.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 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 : Pervasives.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 : Pervasives.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 : Pervasives.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 : Pervasives.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 : Pervasives.out_channel -> unit
Same as close_out
, but ignore all errors.
val set_binary_mode_out : Pervasives.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.
val open_in : string -> Pervasives.in_channel
Open the named file for reading, and return a new input channel on that file, positionned at the beginning of the file.
val open_in_bin : string -> Pervasives.in_channel
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 :
Pervasives.open_flag list ->
int ->
string ->
Pervasives.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. Pervasives.open_in
and Pervasives.open_in_bin
are special cases of this function.
Read one character from the given input channel. Raise End_of_file
if there are no more characters to read.
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.
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 Pervasives.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
.
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
.
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.
Same as Pervasives.input_char
, but return the 8-bit integer representing the character. Raise End_of_file
if an end of file was reached.
Read an integer encoded in binary format (4 bytes, big-endian) 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.
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 : Pervasives.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 : Pervasives.in_channel -> int
Return the current reading position for the given channel.
val in_channel_length : Pervasives.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 : Pervasives.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 : Pervasives.in_channel -> unit
Same as close_in
, but ignore all errors.
val set_binary_mode_in : Pervasives.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
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 = 'a Pervasives.ref = {
mutable contents : 'a;
}
The type of references (mutable indirection cells) containing a value of type 'a
.
Return a fresh reference containing the given value.
!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
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 = ('a, 'b) Pervasives.result =
| Ok of 'a
| Error of 'b
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.
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
.
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
. 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 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.
val (|!) : 'a -> ('a -> 'b) -> 'b
include module type of struct include Either.Export end
type ('f, 's) _either = ('f, 's) Either.t =
| First of 'f
| Second of 's
include module type of struct include Interfaces end
never_returns
should be used as the return type of functions that don't return and might block forever, rather than 'a
or _
. This forces callers of such functions to have a call to never_returns
at the call site, which makes it clear to readers what's going on. We do not intend to use this type for functions such as failwithf
that always raise an exception.
include module type of struct include Perms.Export end
We don't expose bin_io
for write
due to a naming conflict with the functions exported by bin_io
for read_write
. If you want bin_io
for write
, use Write.t
.
module Bool : sig ... end
This module extends the Base Bool
module
This module extends the Base.Queue
module with bin_io support. As a reminder, the Base.Queue
module is a wrapper around OCaml's standard Queue
module that follows Base idioms and adds some functions.
Raised if malloc in C bindings fail (errno * size).
val fst3 : ('a * 'b * 'c) -> 'a
val snd3 : ('a * 'b * 'c) -> 'b
val trd3 : ('a * 'b * 'c) -> 'c
val (==>) : bool -> bool -> bool
val bprintf : Buffer.t -> ('a, Buffer.t, unit) Pervasives.format -> 'a
val const : 'a -> 'b -> 'a
val eprintf : ('a, Pervasives.out_channel, unit) Pervasives.format -> 'a
val failwithf : ('a, unit, string, unit -> 'b) Pervasives.format4 -> 'a
val fprintf :
Pervasives.out_channel ->
('a, Pervasives.out_channel, unit) Pervasives.format ->
'a
val invalid_argf : ('a, unit, string, unit -> 'b) Pervasives.format4 -> 'a
val ksprintf :
(string -> 'a) ->
('b, unit, string, 'a) Pervasives.format4 ->
'b
val phys_equal : 'a -> 'a -> bool
val phys_same : 'a -> 'b -> bool
val printf : ('a, Pervasives.out_channel, unit) Pervasives.format -> 'a
val protect : f:(unit -> 'a) -> finally:(unit -> unit) -> 'a
val protectx : f:('a -> 'b) -> 'a -> finally:('a -> unit) -> 'b
val round : ?dir:[ `Down | `Nearest | `Up | `Zero ] -> Float.t -> Float.t
val sprintf : ('a, unit, string) Pervasives.format -> 'a
val bin_size_sexp_opaque : 'a -> 'a
val bin_write_sexp_opaque : 'a -> 'a
val bin_read_sexp_opaque : 'a -> 'a
Imperative set-like data structure.
Substring type based on Bigarray
, for use in I/O and C-bindings
Module types and utilities for dealing with types that support the bin-io binary encoding.
Packs and unpacks various types of integers into and from strings.
module Blang : sig ... end
A simple boolean domain-specific language
module Blit : sig ... end
This module extends the Base Blit
module
A Bounded_int_table
is a table whose keys can be mapped to integers in a fixed range, 0 ... num_keys-1, where num_keys
is specified at table-creation time. The purpose of Bounded_int_table
is to be faster than Hashtbl
in situations where one is willing to pay a space cost for the speed.
A Bus
is a publisher/subscriber system within the memory space of the program. A bus has a mutable set of subscribers, which can be modified using subscribe_exn
and unsubscribe
.
Conversions between units of measure based on bytes.
module Debug : sig ... end
Utilities for printing debug messages.
module Deque : sig ... end
A double ended queue that can shrink and expand on both ends.
This module extends the Base Either
module
module Error : sig ... end
This module extends the Base Error
module with bin_io
A simple polymorphic functional double-ended queue. Use this if you need a queue-like data structure that provides enqueue and dequeue accessors on both ends. For strictly first-in, first-out access, see Fqueue
.
module Fheap : sig ... end
Functional Heap implementation based on pairing-heap algorithm and immutable data structures. See more info at http://en.wikipedia.org/wiki/Pairing_heap.
module Flags : sig ... end
See flags_intf.ml for documentation.
module Float : sig ... end
An alias to the Float.t
type that causes the sexp and bin-io serializers to fail when provided with nan
or infinity
.
A simple polymorphic functional queue. Use this data structure for strictly first-in, first-out access to a sequence of values. For a similar data structure with enqueue and dequeue accessors on both ends of a sequence, see Fdeque
.
A mutable set of elements
module Heap : sig ... end
Heap implementation based on a pairing-heap.
a signature for identifier types.
module Info : sig ... end
An implementation of compressed integer sets using lists of integer ranges. Operations such as adding and membership are O(n) where n is the number of contigous ranges in the set. For data that is mostly serial, n should remain very small.
Implements a token bucket based throttling rate limiter. This module is useful for limiting network clients to a sensible query rate, or in any case where you have jobs that consume a scarce, but replenishable resource.
A stack implemented with a list. See Stack_intf
for documentation.
This module extends the Base Maybe_bound
module with compare functions in the form of As_lower_bound and As_upper_bound modules.
module Memo : sig ... end
Memoization code -- not re-entrant!
module Month : sig ... end
A Moption
is a mutable option, like 'a option ref
, but with a more efficient implementation; in particular, set_some
does not allocate.
Open this in modules where you don't want to accidentally use polymorphic comparison. Then, use Pervasives.(<), for example, where needed.
This module can be used to safely expose functions and values in signatures that should only be used in unit tests.
This module extends the Base Option
module with bin_io and quickcheck
'a Option_array.t
is a compact representation of 'a option array
: it avoids allocating heap objects representing Some x
, usually representing them with x
instead. It uses a special representation for None
that's guaranteed to never collide with any representation of Some x
.
This module extends the Base Or_error
module
An abstract type of scale factors
module Pool : sig ... end
A polymorphic hashtbl that uses Pool
to avoid allocation.
module Rope : sig ... end
A rope is a standard data structure that represents a single string as a tree of strings, allowing concatenation to do no work up front -- a string formed by many Rope
concatenations followed by a to_string
needs only copy each input to the output once, whereas a string expression looking like a ^ b ^ c ^ ... ^ z
must create an intermediate string for every concatenation, and will copy the original data into and out of short-lived temporary strings many times.
This module extends the Base Option
module with bin_io
This module implements an option ref that starts out as None, and may be set only once. If one tries to set it twice a run time error is generated.
module Sign : sig ... end
This module extends the Base Sign
module with bin_io
A splittable pseudo-random number generator (SPRNG) functions like a PRNG in that it can be used as a stream of random values; it can also be "split" to produce a second, independent stream of random values. This module implements a splittable pseudo-random number generator that sacrifices cryptographic-quality randomness in favor of performance.
The tests generated by these functors are run like any other unit tests: by the inline test runner when the functor is applied.
A thread-safe non-blocking queue of unbounded size.
A ('key, 'value, cmp) Map.t
where every value of type 'key
is present.
module Tuple : sig ... end
Functors and signatures for dealing with modules for tuples.
Witnesses that express whether a type's values are always, sometimes, or never immediate.
Same semantics as 'a Array.t
, except it's guaranteed that the representation array is not tagged with Double_array_tag
, the tag for float arrays. This means it's safer to use in the presence of Obj.magic
, but it's slower than normal Array
if you use it with floats.
Imperative data structure for representing disjoint sets.
Functors for creating modules that mint unique identifiers.
module Unit : sig ... end
Module for the type unit
. This is mostly useful for building functor arguments.
Represents a unit of time, e.g. used by Time.Span.to_string_hum
. Comparison respects Nanosecond < Microsecond < Millisecond < Second < Minute < Hour < Day.
module Univ : sig ... end
An extensible "universal" variant type.
Universal/heterogeneous maps.
A buffer for incremental decoding of an input stream.
See Validated_intf
for documentation.
A weak pointer is a pointer to a heap block that does not cause the heap block to remain live during garbage collection. If the block would otherwise remain live, then then the weak pointer remains pointed to the block. If the block is collected, then the weak pointer is cleared.
include module type of struct include Base.T end
type 'a _maybe_bound = 'a Maybe_bound.t =
| Incl of 'a
| Excl of 'a
| Unbounded
val does_raise : (unit -> 'a) -> bool
type bytes = [
| `This_type_does_not_equal_string_because_we_want_type_errors_to_say_string
]
val am_running_inline_test : bool
Extensible string buffers based on Bigstrings.
String type based on Bigarray
, for use in I/O and C-bindings
Utility functions for marshalling to and from bigstring.
module Date : sig ... end
This module gives access to the same version/build information returned by Command
-based executables when called with the -version
or -build-info
flags by $0 version (-build-info | -version)
or $0 (-build-info | -version)
. Here's how it works: we arrange for the build system to, at link time, include an object file that defines symbols that version_util.ml uses to get the strings that contain the information that this module provides. When building with OMake, our OMakeroot runs build_info.sh to generate *.build_info.c with the symbols and that is linked in.
module Perms : sig ... end
These types are intended to be used as phantom types encoding the permissions on a given type.
To be used in implementing Core, but not by end users