module Stdlib: sig .. end
The OCaml Standard library.
This module is automatically opened at the beginning of each
compilation. All components of this module can therefore be
referred by their short name, without prefixing them by Stdlib
.
It particular, it provides the basic operations over the built-in types (numbers, booleans, byte sequences, strings, exceptions, references, lists, arrays, input-output channels, ...) and the standard library modules.
let raise: exn => 'a;
Raise the given exception value
let raise_notrace: exn => 'a;
A faster version raise
which does not record the backtrace.
let invalid_arg: string => 'a;
Raise exception Invalid_argument
with the given string.
let failwith: string => 'a;
Raise exception Failure
with the given string.
exception Exit;
The Exit
exception is not raised by any library function. It is
provided for use in your programs.
exception Match_failure((string, int, int));
Exception raised when none of the cases of a pattern-matching apply. The arguments are the location of the match keyword in the source code (file name, line number, column number).
exception Assert_failure((string, int, int));
Exception raised when an assertion fails. The arguments are the location of the assert keyword in the source code (file name, line number, column number).
exception Invalid_argument(string);
Exception raised by library functions to signal that the given arguments do not make sense. The string gives some information to the programmer. As a general rule, this exception should not be caught, it denotes a programming error and the code should be modified not to trigger it.
exception Failure(string);
Exception raised by library functions to signal that they are undefined on the given arguments. The string is meant to give some information to the programmer; you must not pattern match on the string literal because it may change in future versions (use Failure _ instead).
exception Not_found;
Exception raised by search functions when the desired object could not be found.
exception Out_of_memory;
Exception raised by the garbage collector when there is insufficient memory to complete the computation. (Not reliable for allocations on the minor heap.)
exception Stack_overflow;
Exception raised by the bytecode interpreter when the evaluation stack reaches its maximal size. This often indicates infinite or excessively deep recursion in the user's program.
Before 4.10, it was not fully implemented by the native-code compiler.
exception Sys_error(string);
Exception raised by the input/output functions to report an operating system error. The string is meant to give some information to the programmer; you must not pattern match on the string literal because it may change in future versions (use Sys_error _ instead).
exception End_of_file;
Exception raised by input functions to signal that the end of file has been reached.
exception Division_by_zero;
Exception raised by integer division and remainder operations when their second argument is zero.
exception Sys_blocked_io;
A special case of Sys_error raised when no I/O is possible on a non-blocking I/O channel.
exception Undefined_recursive_module((string, int, int));
Exception raised when an ill-founded recursive module definition is evaluated. The arguments are the location of the definition in the source code (file name, line number, column number).
let (==): ('a, 'a) => bool;
e1 = e2
tests for structural equality of e1
and e2
.
Mutable structures (e.g. references and arrays) are equal
if and only if their current contents are structurally equal,
even if the two mutable objects are not the same physical object.
Equality between functional values raises Invalid_argument
.
Equality between cyclic data structures may not terminate.
Left-associative operator, see Ocaml_operators
for more information.
let (!=): ('a, 'a) => bool;
Negation of (=)
.
Left-associative operator, see Ocaml_operators
for more information.
let (<): ('a, 'a) => bool;
See (>=)
.
Left-associative operator, see Ocaml_operators
for more information.
let (>): ('a, 'a) => bool;
See (>=)
.
Left-associative operator, see Ocaml_operators
for more information.
let (<=): ('a, 'a) => bool;
See (>=)
.
Left-associative operator, see Ocaml_operators
for more information.
let (>=): ('a, 'a) => bool;
Structural ordering functions. These functions coincide with
the usual orderings over integers, characters, strings, byte sequences
and floating-point numbers, and extend them to a
total ordering over all types.
The ordering is compatible with ( = )
. As in the case
of ( = )
, mutable structures are compared by contents.
Comparison between functional values raises Invalid_argument
.
Comparison between cyclic structures may not terminate.
Left-associative operator, see Ocaml_operators
for more information.
let compare: ('a, 'a) => int;
compare x y
returns 0
if x
is equal to y
,
a negative integer if x
is less than y
, and a positive integer
if x
is greater than y
. The ordering implemented by compare
is compatible with the comparison predicates =
, <
and >
defined above, with one difference on the treatment of the float value
nan
. Namely, the comparison predicates treat nan
as different from any other float value, including itself;
while compare
treats nan
as equal to itself and less than any
other float value. This treatment of nan
ensures that compare
defines a total ordering relation.
compare
applied to functional values may raise Invalid_argument
.
compare
applied to cyclic structures may not terminate.
The compare
function can be used as the comparison function
required by the Set.Make
and Map.Make
functors, as well as
the List.sort
and Array.sort
functions.
let min: ('a, 'a) => 'a;
Return the smaller of the two arguments.
The result is unspecified if one of the arguments contains
the float value nan
.
let max: ('a, 'a) => 'a;
Return the greater of the two arguments.
The result is unspecified if one of the arguments contains
the float value nan
.
let (===): ('a, 'a) => bool;
e1 == e2
tests for physical equality of e1
and e2
.
On mutable types such as references, arrays, byte sequences, records with
mutable fields and objects with mutable instance variables,
e1 == e2
is true if and only if physical modification of e1
also affects e2
.
On non-mutable types, the behavior of ( == )
is
implementation-dependent; however, it is guaranteed that
e1 == e2
implies compare e1 e2 = 0
.
Left-associative operator, see Ocaml_operators
for more information.
let (!==): ('a, 'a) => bool;
Negation of (==)
.
Left-associative operator, see Ocaml_operators
for more information.
let (!): bool => bool;
The boolean negation.
let (&&): (bool, bool) => bool;
The boolean 'and'. Evaluation is sequential, left-to-right:
in e1 && e2
, e1
is evaluated first, and if it returns false
,
e2
is not evaluated at all.
Right-associative operator, see Ocaml_operators
for more information.
let (&): (bool, bool) => bool;
(&&)
should be used instead.
Right-associative operator, see Ocaml_operators
for more information.let (||): (bool, bool) => bool;
The boolean 'or'. Evaluation is sequential, left-to-right:
in e1 || e2
, e1
is evaluated first, and if it returns true
,
e2
is not evaluated at all.
Right-associative operator, see Ocaml_operators
for more information.
let (or): (bool, bool) => bool;
(||)
should be used instead.
Right-associative operator, see Ocaml_operators
for more information.let __LOC__: string;
__LOC__
returns the location at which this expression appears in
the file currently being parsed by the compiler, with the standard
error format of OCaml: "File %S, line %d, characters %d-%d".
let __FILE__: string;
__FILE__
returns the name of the file currently being
parsed by the compiler.
let __LINE__: int;
__LINE__
returns the line number at which this expression
appears in the file currently being parsed by the compiler.
let __MODULE__: string;
__MODULE__
returns the module name of the file being
parsed by the compiler.
let __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.
let __FUNCTION__: string;
__FUNCTION__
returns the name of the current function or method, including
any enclosing modules or classes.
let __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".
let __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.
let __POS_OF__: 'a => ((string, int, int, int), 'a);
__POS_OF__ expr
returns a pair (loc,expr)
, where loc
is a
tuple (file,lnum,cnum,enum)
corresponding to the location at
which the expression expr
appears in the file currently being
parsed by the compiler. file
is the current filename, lnum
the
line number, cnum
the character position in the line and enum
the last character position in the line.
let (|>): ('a, 'a => 'b) => 'b;
Reverse-application operator: x |> f |> g
is exactly equivalent
to g (f (x))
.
Left-associative operator, see Ocaml_operators
for more information.
let (@@): ('a => 'b, 'a) => 'b;
Application operator: g @@ f @@ x
is exactly equivalent to
g (f (x))
.
Right-associative operator, see Ocaml_operators
for more information.
Integers are Sys.int_size
bits wide.
All operations are taken modulo 2Sys.int_size
.
They do not fail on overflow.
let (~-): int => int;
Unary negation. You can also write - e
instead of ~- e
.
Unary operator, see Ocaml_operators
for more information.
let (~+): int => int;
Unary addition. You can also write + e
instead of ~+ e
.
Unary operator, see Ocaml_operators
for more information.
let succ: int => int;
succ x
is x + 1
.
let pred: int => int;
pred x
is x - 1
.
let (+): (int, int) => int;
Integer addition.
Left-associative operator, see Ocaml_operators
for more information.
let (-): (int, int) => int;
Integer subtraction.
Left-associative operator, , see Ocaml_operators
for more information.
let ( * ): (int, int) => int;
Integer multiplication.
Left-associative operator, see Ocaml_operators
for more information.
let (/): (int, int) => int;
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.
Division_by_zero
if the second argument is 0.let (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
.
Left-associative operator, see Ocaml_operators
for more information.
Division_by_zero
if y
is zero.let abs: int => int;
Return the absolute value of the argument. Note that this may be
negative if the argument is min_int
.
let max_int: int;
The greatest representable integer.
let min_int: int;
The smallest representable integer.
let (land): (int, int) => int;
Bitwise logical and.
Left-associative operator, see Ocaml_operators
for more information.
let (lor): (int, int) => int;
Bitwise logical or.
Left-associative operator, see Ocaml_operators
for more information.
let (lxor): (int, int) => int;
Bitwise logical exclusive or.
Left-associative operator, see Ocaml_operators
for more information.
let lnot: int => int;
Bitwise logical negation.
let (lsl): (int, int) => int;
n lsl m
shifts n
to the left by m
bits.
The result is unspecified if m < 0
or m > Sys.int_size
.
Right-associative operator, see Ocaml_operators
for more information.
let (lsr): (int, int) => int;
n lsr m
shifts n
to the right by m
bits.
This is a logical shift: zeroes are inserted regardless of
the sign of n
.
The result is unspecified if m < 0
or m > Sys.int_size
.
Right-associative operator, see Ocaml_operators
for more information.
let (asr): (int, int) => int;
n asr m
shifts n
to the right by m
bits.
This is an arithmetic shift: the sign bit of n
is replicated.
The result is unspecified if m < 0
or m > Sys.int_size
.
Right-associative operator, see Ocaml_operators
for more information.
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
, ...
let (~-.): float => float;
Unary negation. You can also write -. e
instead of ~-. e
.
Unary operator, see Ocaml_operators
for more information.
let (~+.): float => float;
Unary addition. You can also write +. e
instead of ~+. e
.
Unary operator, see Ocaml_operators
for more information.
let (+.): (float, float) => float;
Floating-point addition.
Left-associative operator, see Ocaml_operators
for more information.
let (-.): (float, float) => float;
Floating-point subtraction.
Left-associative operator, see Ocaml_operators
for more information.
let ( *. ): (float, float) => float;
Floating-point multiplication.
Left-associative operator, see Ocaml_operators
for more information.
let (/.): (float, float) => float;
Floating-point division.
Left-associative operator, see Ocaml_operators
for more information.
let ( ** ): (float, float) => float;
Exponentiation.
Right-associative operator, see Ocaml_operators
for more information.
let sqrt: float => float;
Square root.
let exp: float => float;
Exponential.
let log: float => float;
Natural logarithm.
let log10: float => float;
Base 10 logarithm.
let expm1: float => float;
expm1 x
computes exp x -. 1.0
, giving numerically-accurate results
even if x
is close to 0.0
.
let log1p: float => float;
log1p x
computes log(1.0 +. x)
(natural logarithm),
giving numerically-accurate results even if x
is close to 0.0
.
let cos: float => float;
Cosine. Argument is in radians.
let sin: float => float;
Sine. Argument is in radians.
let tan: float => float;
Tangent. Argument is in radians.
let 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
.
let 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
.
let atan: float => float;
Arc tangent.
Result is in radians and is between -pi/2
and pi/2
.
let 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
.
let hypot: (float, float) => float;
hypot x y
returns sqrt(x *. x + y *. y)
, that is, the length
of the hypotenuse of a right-angled triangle with sides of length
x
and y
, or, equivalently, the distance of the point (x,y)
to origin. If one of x
or y
is infinite, returns infinity
even if the other is nan
.
let cosh: float => float;
Hyperbolic cosine. Argument is in radians.
let sinh: float => float;
Hyperbolic sine. Argument is in radians.
let tanh: float => float;
Hyperbolic tangent. Argument is in radians.
let 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.
let 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.
let abs_float: float => float;
abs_float f
returns the absolute value of f
.
let 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.
let 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.
let 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
.
let ldexp: (float, int) => float;
ldexp x n
returns x *. 2 ** n
.
let modf: float => (float, float);
modf f
returns the pair of the fractional and integral
part of f
.
let float: int => float;
Same as float_of_int
.
let float_of_int: int => float;
Convert an integer to floating-point.
let truncate: float => int;
Same as int_of_float
.
let 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.
let infinity: float;
Positive infinity.
let neg_infinity: float;
Negative infinity.
let nan: float;
A special floating-point value denoting the result of an
undefined operation such as 0.0 /. 0.0
. Stands for
'not a number'. Any floating-point operation with nan
as
argument returns nan
as result. As for floating-point comparisons,
=
, <
, <=
, >
and >=
return false
and <>
returns true
if one or both of their arguments is nan
.
let max_float: float;
The largest positive finite value of type float
.
let min_float: float;
The smallest positive, non-zero, non-denormalized value of type float
.
let epsilon_float: float;
The difference between 1.0
and the smallest exactly representable
floating-point number greater than 1.0
.
type fpclass =
| |
FP_normal |
(* | Normal number, none of the below | *) |
| |
FP_subnormal |
(* | Number very close to 0.0, has reduced precision | *) |
| |
FP_zero |
(* | Number is 0.0 or -0.0 | *) |
| |
FP_infinite |
(* | Number is positive or negative infinity | *) |
| |
FP_nan |
(* | Not a number: result of an undefined operation | *) |
The five classes of floating-point numbers, as determined by
the classify_float
function.
let classify_float: float => fpclass;
Return the class of the given floating-point number: normal, subnormal, zero, infinite, or not a number.
More string operations are provided in module String
.
let (++): (string, string) => string;
String concatenation.
Right-associative operator, see Ocaml_operators
for more information.
More character operations are provided in module Char
.
let int_of_char: char => int;
Return the ASCII code of the argument.
let char_of_int: int => char;
Return the character with the given ASCII code.
Invalid_argument
if the argument is
outside the range 0--255.let ignore: 'a => unit;
Discard the value of its argument and return ()
.
For instance, ignore(f x)
discards the result of
the side-effecting function f
. It is equivalent to
f x; ()
, except that the latter may generate a
compiler warning; writing ignore(f x)
instead
avoids the warning.
let 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.
let bool_of_string_opt: string => option(bool);
Convert the given string to a boolean.
Return None
if the string is not "true"
or "false"
.
let bool_of_string: string => bool;
Same as bool_of_string_opt
, but raise
Invalid_argument "bool_of_string"
instead of returning None
.
let string_of_int: int => string;
Return the string representation of an integer, in decimal.
let int_of_string_opt: string => option(int);
Convert the given string to an integer.
The string is read in decimal (by default, or if the string
begins with 0u
), in hexadecimal (if it begins with 0x
or
0X
), in octal (if it begins with 0o
or 0O
), or in binary
(if it begins with 0b
or 0B
).
The 0u
prefix reads the input as an unsigned integer in the range
[0, 2*max_int+1]
. If the input exceeds max_int
it is converted to the signed integer
min_int + input - max_int - 1
.
The _
(underscore) character can appear anywhere in the string
and is ignored.
Return None
if the given string is not a valid representation of an
integer, or if the integer represented exceeds the range of integers
representable in type int
.
let int_of_string: string => int;
Same as int_of_string_opt
, but raise
Failure "int_of_string"
instead of returning None
.
let string_of_float: float => string;
Return the string representation of a floating-point number.
let float_of_string_opt: string => option(float);
Convert the given string to a float. The string is read in decimal
(by default) or in hexadecimal (marked by 0x
or 0X
).
The format of decimal floating-point numbers is
[-] dd.ddd (e|E) [+|-] dd
, where d
stands for a decimal digit.
The format of hexadecimal floating-point numbers is
[-] 0(x|X) hh.hhh (p|P) [+|-] dd
, where h
stands for an
hexadecimal digit and d
for a decimal digit.
In both cases, at least one of the integer and fractional parts must be given; the exponent part is optional.
The _
(underscore) character can appear anywhere in the string
and is ignored.
Depending on the execution platforms, other representations of floating-point numbers can be accepted, but should not be relied upon.
Return None
if the given string is not a valid representation of a float.
let float_of_string: string => float;
Same as float_of_string_opt
, but raise
Failure "float_of_string"
instead of returning None
.
let fst: (('a, 'b)) => 'a;
Return the first component of a pair.
let snd: (('a, 'b)) => 'b;
Return the second component of a pair.
More list operations are provided in module List
.
let (@): (list('a), list('a)) => list('a);
List concatenation. Not tail-recursive (length of the first argument).
Right-associative operator, see Ocaml_operators
for more information.
Note: all input/output functions can raise Sys_error
when the system
calls they invoke fail.
type in_channel;
The type of input channel.
type out_channel;
The type of output channel.
let stdin: in_channel;
The standard input for the process.
let stdout: out_channel;
The standard output for the process.
let stderr: out_channel;
The standard error output for the process.
let print_char: char => unit;
Print a character on standard output.
let print_string: string => unit;
Print a string on standard output.
let print_bytes: bytes => unit;
Print a byte sequence on standard output.
let print_int: int => unit;
Print an integer, in decimal, on standard output.
let print_float: float => unit;
Print a floating-point number, in decimal, on standard output.
let print_endline: string => unit;
Print a string, followed by a newline character, on standard output and flush standard output.
let 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.
let prerr_char: char => unit;
Print a character on standard error.
let prerr_string: string => unit;
Print a string on standard error.
let prerr_bytes: bytes => unit;
Print a byte sequence on standard error.
let prerr_int: int => unit;
Print an integer, in decimal, on standard error.
let prerr_float: float => unit;
Print a floating-point number, in decimal, on standard error.
let prerr_endline: string => unit;
Print a string, followed by a newline character on standard error and flush standard error.
let prerr_newline: unit => unit;
Print a newline character on standard error, and flush standard error.
let 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.
let read_int_opt: unit => option(int);
Flush standard output, then read one line from standard input and convert it to an integer.
Return None
if the line read is not a valid representation of an integer.
let read_int: unit => int;
Same as read_int_opt
, but raise Failure "int_of_string"
instead of returning None
.
let read_float_opt: unit => option(float);
Flush standard output, then read one line from standard input and convert it to a floating-point number.
Return None
if the line read is not a valid representation of a
floating-point number.
let read_float: unit => float;
Same as read_float_opt
, but raise Failure "float_of_string"
instead of returning None
.
type open_flag =
| |
Open_rdonly |
(* | open for reading. | *) |
| |
Open_wronly |
(* | open for writing. | *) |
| |
Open_append |
(* | open for appending: always write at end of file. | *) |
| |
Open_creat |
(* | create the file if it does not exist. | *) |
| |
Open_trunc |
(* | empty the file if it already exists. | *) |
| |
Open_excl |
(* | fail if Open_creat and the file already exists. | *) |
| |
Open_binary |
(* | open in binary mode (no conversion). | *) |
| |
Open_text |
(* | open in text mode (may perform conversions). | *) |
| |
Open_nonblock |
(* | open in non-blocking mode. | *) |
Opening modes for open_out_gen
and
open_in_gen
.
let open_out: string => out_channel;
Open the named file for writing, and return a new output channel on that file, positioned at the beginning of the file. The file is truncated to zero length if it already exists. It is created if it does not already exists.
let open_out_bin: string => out_channel;
let open_out_gen: (list(open_flag), int, string) => out_channel;
open_out_gen mode perm filename
opens the named file for writing,
as described above. The extra argument mode
specifies the opening mode. The extra argument perm
specifies
the file permissions, in case the file must be created.
open_out
and open_out_bin
are special
cases of this function.
let flush: out_channel => unit;
Flush the buffer associated with the given output channel, performing all pending writes on that channel. Interactive programs must be careful about flushing standard output and standard error at the right time.
let flush_all: unit => unit;
Flush all open output channels; ignore errors.
let output_char: (out_channel, char) => unit;
Write the character on the given output channel.
let output_string: (out_channel, string) => unit;
Write the string on the given output channel.
let output_bytes: (out_channel, bytes) => unit;
Write the byte sequence on the given output channel.
let output: (out_channel, bytes, int, int) => unit;
output oc buf pos len
writes len
characters from byte sequence buf
,
starting at offset pos
, to the given output channel oc
.
Invalid_argument
if pos
and len
do not
designate a valid range of buf
.let output_substring: (out_channel, string, int, int) => unit;
Same as output
but take a string as argument instead of
a byte sequence.
let output_byte: (out_channel, int) => unit;
Write one 8-bit integer (as the single character with that code) on the given output channel. The given integer is taken modulo 256.
let output_binary_int: (out_channel, int) => unit;
Write one integer in binary format (4 bytes, big-endian)
on the given output channel.
The given integer is taken modulo 232.
The only reliable way to read it back is through the
input_binary_int
function. The format is compatible across
all machines for a given version of OCaml.
let output_value: (out_channel, 'a) => unit;
Write the representation of a structured value of any type
to a channel. Circularities and sharing inside the value
are detected and preserved. The object can be read back,
by the function input_value
. See the description of module
Marshal
for more information. output_value
is equivalent
to Marshal.to_channel
with an empty list of flags.
let 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.
let pos_out: out_channel => int;
Return the current writing position for the given channel. Does
not work on channels opened with the Open_append
flag (returns
unspecified results).
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_out
, then going back to
this position using seek_out
will not work. For this
programming idiom to work reliably and portably, the file must be
opened in binary mode.
let out_channel_length: out_channel => int;
Return the size (number of characters) of the regular file on which the given channel is opened. If the channel is opened on a file that is not a regular file, the result is meaningless.
let close_out: out_channel => unit;
Close the given channel, flushing all buffered write operations.
Output functions raise a Sys_error
exception when they are
applied to a closed output channel, except close_out
and flush
,
which do nothing when applied to an already closed channel.
Note that close_out
may raise Sys_error
if the operating
system signals an error when flushing or closing.
let close_out_noerr: out_channel => unit;
Same as close_out
, but ignore all errors.
let set_binary_mode_out: (out_channel, bool) => unit;
set_binary_mode_out oc true
sets the channel oc
to binary
mode: no translations take place during output.
set_binary_mode_out oc false
sets the channel oc
to text
mode: depending on the operating system, some translations
may take place during output. For instance, under Windows,
end-of-lines will be translated from \n
to \r\n
.
This function has no effect under operating systems that
do not distinguish between text mode and binary mode.
let open_in: string => in_channel;
Open the named file for reading, and return a new input channel on that file, positioned at the beginning of the file.
let open_in_bin: string => in_channel;
let open_in_gen: (list(open_flag), int, string) => in_channel;
open_in_gen mode perm filename
opens the named file for reading,
as described above. The extra arguments
mode
and perm
specify the opening mode and file permissions.
open_in
and open_in_bin
are special
cases of this function.
let input_char: in_channel => char;
Read one character from the given input channel.
End_of_file
if there are no more characters to read.let input_line: in_channel => string;
Read characters from the given input channel, until a newline character is encountered. Return the string of all characters read, without the newline character at the end.
End_of_file
if the end of the file is reached
at the beginning of line.let input: (in_channel, bytes, int, int) => int;
input ic buf pos len
reads up to len
characters from
the given channel ic
, storing them in byte sequence buf
, starting at
character number pos
.
It returns the actual number of characters read, between 0 and
len
(inclusive).
A return value of 0 means that the end of file was reached.
A return value between 0 and len
exclusive means that
not all requested len
characters were read, either because
no more characters were available at that time, or because
the implementation found it convenient to do a partial read;
input
must be called again to read the remaining characters,
if desired. (See also really_input
for reading
exactly len
characters.)
Exception Invalid_argument "input"
is raised if pos
and len
do not designate a valid range of buf
.
let really_input: (in_channel, bytes, int, int) => unit;
really_input ic buf pos len
reads len
characters from channel ic
,
storing them in byte sequence buf
, starting at character number pos
.
End_of_file
if the end of file is reached before len
characters have been read.Invalid_argument
if
pos
and len
do not designate a valid range of buf
.let really_input_string: (in_channel, int) => string;
really_input_string ic len
reads len
characters from channel ic
and returns them in a new string.
End_of_file
if the end of file is reached before len
characters have been read.let input_byte: in_channel => int;
Same as input_char
, but return the 8-bit integer representing
the character.
End_of_file
if an end of file was reached.let input_binary_int: in_channel => int;
Read an integer encoded in binary format (4 bytes, big-endian)
from the given input channel. See output_binary_int
.
End_of_file
if an end of file was reached while reading the
integer.let input_value: in_channel => 'a;
Read the representation of a structured value, as produced
by output_value
, and return the corresponding value.
This function is identical to Marshal.from_channel
;
see the description of module Marshal
for more information,
in particular concerning the lack of type safety.
let 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.
let 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.
let 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.
let 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.
let close_in_noerr: in_channel => unit;
Same as close_in
, but ignore all errors.
let 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.
module LargeFile: sig .. end
Operations on large files.
type 'a ref = {
|
mutable contents : 'a; |
}
The type of references (mutable indirection cells) containing
a value of type 'a
.
let ref: 'a => ref('a);
Return a fresh reference containing the given value.
let (^): ref('a) => 'a;
!r
returns the current contents of reference r
.
Equivalent to fun r -> r.contents
.
Unary operator, see Ocaml_operators
for more information.
let (:=): (ref('a), '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.
let incr: ref(int) => unit;
Increment the integer contained in the given reference.
Equivalent to fun r -> r := succ !r
.
let decr: ref(int) => unit;
Decrement the integer contained in the given reference.
Equivalent to fun r -> r := pred !r
.
type ('a, 'b) 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:
'%'
followed by one or more characters specifying what kind of argument to
read or print,'@'
followed by one or more characters specifying how to read or print the
argument,There is an additional lexical rule to escape the special characters '%'
and '@'
in format strings: if a special character follows a '%'
character, it is treated as a plain character. In other words, "%%"
is
considered as a plain '%'
and "%@"
as a plain '@'
.
For more information about conversion specifications and formatting
indications available, read the documentation of modules Scanf
,
Printf
and Format
.
Format strings have a general and highly polymorphic type
('a, 'b, 'c, 'd, 'e, 'f) format6
.
The two simplified types, format
and format4
below are
included for backward compatibility with earlier releases of
OCaml.
The meaning of format string type parameters is as follows:
'a
is the type of the parameters of the format for formatted output
functions (printf
-style functions);
'a
is the type of the values read by the format for formatted input
functions (scanf
-style functions).'b
is the type of input source for formatted input functions and the
type of output target for formatted output functions.
For printf
-style functions from module Printf
, 'b
is typically
out_channel
;
for printf
-style functions from module Format
, 'b
is typically
Format.formatter
;
for scanf
-style functions from module Scanf
, 'b
is typically
Scanf.Scanning.in_channel
.Type argument 'b
is also the type of the first argument given to
user's defined printing functions for %a
and %t
conversions,
and user's defined reading functions for %r
conversion.
'c
is the type of the result of the %a
and %t
printing
functions, and also the type of the argument transmitted to the
first argument of kprintf
-style functions or to the
kscanf
-style functions.'d
is the type of parameters for the scanf
-style functions.'e
is the type of the receiver function for the scanf
-style functions.'f
is the final result type of a formatted input/output function
invocation: for the printf
-style functions, it is typically unit
;
for the scanf
-style functions, it is typically the result type of the
receiver function.type format6('a, 'b, 'c, 'd, 'e, 'f) =
CamlinternalFormatBasics.format6('a, 'b, 'c, 'd, 'e, 'f);
type format4('a, 'b, 'c, 'd) = format6('a, 'b, 'c, 'c, 'c, 'd);
type format('a, 'b, 'c) = format4('a, 'b, 'c, 'c);
let string_of_format: format6('a, 'b, 'c, 'd, 'e, 'f) => string;
Converts a format string into a string.
let format_of_string:
format6('a, 'b, 'c, 'd, 'e, 'f) => format6('a, 'b, 'c, 'd, 'e, 'f);
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.
let (^^):
(format6('a, 'b, 'c, 'd, 'e, 'f), format6('f, 'b, 'c, 'e, 'g, 'h)) =>
format6('a, 'b, 'c, 'd, 'g, 'h);
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.
let exit: int => 'a;
Terminate the process, returning the given status code
to the operating system: usually 0 to indicate no errors,
and a small positive integer to indicate failure.
All open output channels are flushed with flush_all
.
An implicit exit 0
is performed each time a program
terminates normally. An implicit exit 2
is performed if the program
terminates early because of an uncaught exception.
let at_exit: (unit => unit) => unit;
Register the given function to be called at program termination
time. The functions registered with at_exit
will be called when
the program does any of the following:
exit
caml_shutdown
.
The functions are called in 'last in, first out' order: the
function most recently added with at_exit
is called first.module Arg: Arg;
module Array: Array;
module ArrayLabels: ArrayLabels;
module Atomic: Atomic;
module Bigarray: Bigarray;
module Bool: Bool;
module Buffer: Buffer;
module Bytes: Bytes;
module BytesLabels: BytesLabels;
module Callback: Callback;
module Char: Char;
module Complex: Complex;
module Digest: Digest;
module Either: Either;
module Ephemeron: Ephemeron;
module Filename: Filename;
module Float: Float;
module Format: Format;
module Fun: Fun;
module Gc: Gc;
module Genlex: Genlex;
module Hashtbl: Hashtbl;
module Int: Int;
module Int32: Int32;
module Int64: Int64;
module Lazy: Lazy;
module Lexing: Lexing;
module List: List;
module ListLabels: ListLabels;
module Map: Map;
module Marshal: Marshal;
module MoreLabels: MoreLabels;
module Nativeint: Nativeint;
module Obj: Obj;
module Oo: Oo;
module Option: Option;
module Parsing: Parsing;
module Pervasives: Pervasives;
module Printexc: Printexc;
module Printf: Printf;
module Queue: Queue;
module Random: Random;
module Result: Result;
module Scanf: Scanf;
module Seq: Seq;
module Set: Set;
module Stack: Stack;
module StdLabels: StdLabels;
module Stream: Stream;
module String: String;
module StringLabels: StringLabels;
module Sys: Sys;
module Uchar: Uchar;
module Unit: Unit;
module Weak: Weak;