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 builtin types (numbers, booleans, byte sequences, strings, exceptions, references, lists, arrays, inputoutput channels, ...) and the standard library modules.
val raise : exn > 'a
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.
exception Exit
The Exit
exception is not raised by any library function. It is provided for use in your programs.
exception Match_failure of (string * int * int)
Exception raised when none of the cases of a patternmatching apply. The arguments are the location of the match keyword in the source code (file name, line number, column number).
exception Assert_failure of (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 of 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 of 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 nativecode compiler.
exception Sys_error of 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 nonblocking I/O channel.
exception Undefined_recursive_module of (string * int * int)
Exception raised when an illfounded recursive module definition is evaluated. The arguments are the location of the definition in the source code (file name, line number, column number).
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. Leftassociative operator, see Ocaml_operators
for more information.
val (<>) : 'a > 'a > bool
Negation of (=)
. Leftassociative operator, see Ocaml_operators
for more information.
val (<) : 'a > 'a > bool
See (>=)
. Leftassociative operator, see Ocaml_operators
for more information.
val (>) : 'a > 'a > bool
See (>=)
. Leftassociative operator, see Ocaml_operators
for more information.
val (<=) : 'a > 'a > bool
See (>=)
. Leftassociative operator, see Ocaml_operators
for more information.
val (>=) : 'a > 'a > bool
Structural ordering functions. These functions coincide with the usual orderings over integers, characters, strings, byte sequences and floatingpoint numbers, and extend them to a total ordering over all types. The ordering is compatible with ( = )
. As in the case of ( = )
, mutable structures are compared by contents. Comparison between functional values raises Invalid_argument
. Comparison between cyclic structures may not terminate. Leftassociative operator, see Ocaml_operators
for more information.
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 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.
val 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
.
val 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
.
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 nonmutable types, the behavior of ( == )
is implementationdependent; however, it is guaranteed that e1 == e2
implies compare e1 e2 = 0
. Leftassociative operator, see Ocaml_operators
for more information.
val (!=) : 'a > 'a > bool
Negation of (==)
. Leftassociative operator, see Ocaml_operators
for more information.
val not : bool > bool
The boolean negation.
val (&&) : bool > bool > bool
The boolean 'and'. Evaluation is sequential, lefttoright: in e1 && e2
, e1
is evaluated first, and if it returns false
, e2
is not evaluated at all. Rightassociative operator, see Ocaml_operators
for more information.
val (&) : bool > bool > bool
(&&)
should be used instead. Rightassociative operator, see Ocaml_operators
for more information.val () : bool > bool > bool
The boolean 'or'. Evaluation is sequential, lefttoright: in e1  e2
, e1
is evaluated first, and if it returns true
, e2
is not evaluated at all. Rightassociative operator, see Ocaml_operators
for more information.
val (or) : bool > bool > bool
()
should be used instead. Rightassociative operator, see Ocaml_operators
for more information.val __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".
val __FILE__ : string
__FILE__
returns the name of the file currently being parsed by the compiler.
val __LINE__ : int
__LINE__
returns the line number at which this expression appears in the file currently being parsed by the compiler.
val __MODULE__ : string
__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 (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.
val (>) : 'a > ('a > 'b) > 'b
Reverseapplication operator: x > f > g
is exactly equivalent to g (f (x))
. Leftassociative operator, see Ocaml_operators
for more information.
val (@@) : ('a > 'b) > 'a > 'b
Application operator: g @@ f @@ x
is exactly equivalent to g (f (x))
. Rightassociative operator, see Ocaml_operators
for more information.
Integers are Sys.int_size
bits wide. All operations are taken modulo 2^{Sys.int_size}. They do not fail on overflow.
val (~) : int > int
Unary negation. You can also write  e
instead of ~ e
. Unary operator, see Ocaml_operators
for more information.
val (~+) : int > int
Unary addition. You can also write + e
instead of ~+ e
. Unary operator, see Ocaml_operators
for more information.
val succ : int > int
succ x
is x + 1
.
val pred : int > int
pred x
is x  1
.
val (+) : int > int > int
Integer addition. Leftassociative operator, see Ocaml_operators
for more information.
val () : int > int > int
Integer subtraction. Leftassociative operator, , see Ocaml_operators
for more information.
val ( * ) : int > int > int
Integer multiplication. Leftassociative operator, see Ocaml_operators
for more information.
val (/) : 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)
. Leftassociative operator, see Ocaml_operators
for more information.
Division_by_zero
if the second argument is 0.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
. Leftassociative operator, see Ocaml_operators
for more information.
Division_by_zero
if y
is zero.val abs : int > int
Return the absolute value of the argument. Note that this may be negative if the argument is min_int
.
val max_int : int
The greatest representable integer.
val min_int : int
The smallest representable integer.
val (land) : int > int > int
Bitwise logical and. Leftassociative operator, see Ocaml_operators
for more information.
val (lor) : int > int > int
Bitwise logical or. Leftassociative operator, see Ocaml_operators
for more information.
val (lxor) : int > int > int
Bitwise logical exclusive or. Leftassociative operator, see Ocaml_operators
for more information.
val lnot : int > int
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 > Sys.int_size
. Rightassociative operator, see Ocaml_operators
for more information.
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 > Sys.int_size
. Rightassociative operator, see Ocaml_operators
for more information.
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 > Sys.int_size
. Rightassociative operator, see Ocaml_operators
for more information.
OCaml's floatingpoint numbers follow the IEEE 754 standard, using double precision (64 bits) numbers. Floatingpoint operations never raise an exception on overflow, underflow, division by zero, etc. Instead, special IEEE numbers are returned as appropriate, such as infinity
for 1.0 /. 0.0
, neg_infinity
for 1.0 /. 0.0
, and nan
('not a number') for 0.0 /. 0.0
. These special numbers then propagate through floatingpoint computations as expected: for instance, 1.0 /. infinity
is 0.0
, and any arithmetic operation with nan
as argument returns nan
as result.
val (~.) : float > float
Unary negation. You can also write . e
instead of ~. e
. Unary operator, see Ocaml_operators
for more information.
val (~+.) : float > float
Unary addition. You can also write +. e
instead of ~+. e
. Unary operator, see Ocaml_operators
for more information.
val (+.) : float > float > float
Floatingpoint addition. Leftassociative operator, see Ocaml_operators
for more information.
val (.) : float > float > float
Floatingpoint subtraction. Leftassociative operator, see Ocaml_operators
for more information.
val ( *. ) : float > float > float
Floatingpoint multiplication. Leftassociative operator, see Ocaml_operators
for more information.
val (/.) : float > float > float
Floatingpoint division. Leftassociative operator, see Ocaml_operators
for more information.
val ( ** ) : float > float > float
Exponentiation. Rightassociative operator, see Ocaml_operators
for more information.
val sqrt : float > float
Square root.
val exp : float > float
Exponential.
val log : float > float
Natural logarithm.
val log10 : float > float
Base 10 logarithm.
val expm1 : float > float
expm1 x
computes exp x . 1.0
, giving numericallyaccurate results even if x
is close to 0.0
.
val log1p : float > float
log1p x
computes log(1.0 +. x)
(natural logarithm), giving numericallyaccurate results even if x
is close to 0.0
.
val cos : float > float
Cosine. Argument is in radians.
val sin : float > float
Sine. Argument is in radians.
val tan : float > float
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 rightangled 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
.
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 nonzero, they are defined by f = x *. 2 ** n
and 0.5 <= x < 1.0
.
val ldexp : float > int > float
ldexp x n
returns x *. 2 ** n
.
val modf : float > float * float
modf f
returns the pair of the fractional and integral part of f
.
val float : int > float
Same as float_of_int
.
val float_of_int : int > float
Convert an integer to floatingpoint.
val truncate : float > int
Same as int_of_float
.
val int_of_float : float > int
Truncate the given floatingpoint number to an integer. The result is unspecified if the argument is nan
or falls outside the range of representable integers.
val infinity : float
Positive infinity.
val neg_infinity : float
Negative infinity.
val nan : float
A special floatingpoint value denoting the result of an undefined operation such as 0.0 /. 0.0
. Stands for 'not a number'. Any floatingpoint operation with nan
as argument returns nan
as result. As for floatingpoint comparisons, =
, <
, <=
, >
and >=
return false
and <>
returns true
if one or both of their arguments is nan
.
val max_float : float
The largest positive finite value of type float
.
val min_float : float
The smallest positive, nonzero, nondenormalized value of type float
.
val epsilon_float : float
The difference between 1.0
and the smallest exactly representable floatingpoint 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 floatingpoint numbers, as determined by the classify_float
function.
val classify_float : float > fpclass
Return the class of the given floatingpoint number: normal, subnormal, zero, infinite, or not a number.
More string operations are provided in module String
.
val (^) : string > string > string
String concatenation. Rightassociative operator, see Ocaml_operators
for more information.
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.
Invalid_argument
if the argument is outside the range 0255.val ignore : 'a > unit
Discard the value of its argument and return ()
. For instance, ignore(f x)
discards the result of the sideeffecting function f
. It is equivalent to f x; ()
, except that the latter may generate a compiler warning; writing ignore(f x)
instead avoids the warning.
val string_of_bool : 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_opt : string > bool option
Convert the given string to a boolean.
Return None
if the string is not "true"
or "false"
.
val bool_of_string : string > bool
Same as bool_of_string_opt
, but raise Invalid_argument "bool_of_string"
instead of returning None
.
val string_of_int : int > string
Return the string representation of an integer, in decimal.
val int_of_string_opt : string > int option
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
.
val int_of_string : string > int
Same as int_of_string_opt
, but raise Failure "int_of_string"
instead of returning None
.
val string_of_float : float > string
Return the string representation of a floatingpoint number.
val float_of_string_opt : string > float option
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 floatingpoint numbers is [] dd.ddd (eE) [+] dd
, where d
stands for a decimal digit.
The format of hexadecimal floatingpoint numbers is [] 0(xX) hh.hhh (pP) [+] 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 floatingpoint numbers can be accepted, but should not be relied upon.
Return None
if the given string is not a valid representation of a float.
val float_of_string : string > float
Same as float_of_string_opt
, but raise Failure "float_of_string"
instead of returning None
.
val fst : 'a * 'b > 'a
Return the first component of a pair.
val snd : 'a * 'b > 'b
Return the second component of a pair.
More list operations are provided in module List
.
val (@) : 'a list > 'a list > 'a list
List concatenation. Not tailrecursive (length of the first argument). Rightassociative 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.
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.
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 floatingpoint 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.
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 floatingpoint 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_opt : unit > int option
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.
val read_int : unit > int
Same as read_int_opt
, but raise Failure "int_of_string"
instead of returning None
.
val read_float_opt : unit > float option
Flush standard output, then read one line from standard input and convert it to a floatingpoint number.
Return None
if the line read is not a valid representation of a floatingpoint number.
val 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 nonblocking mode. 
*) 
Opening modes for open_out_gen
and open_in_gen
.
val 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.
val open_out_bin : string > out_channel
val open_out_gen : open_flag list > 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.
val 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.
val flush_all : unit > unit
Flush all open output channels; ignore errors.
val output_char : out_channel > char > unit
Write the character on the given output channel.
val output_string : out_channel > string > unit
Write the string on the given output channel.
val output_bytes : out_channel > bytes > unit
Write the byte sequence on the given output channel.
val 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
.val output_substring : out_channel > string > int > int > unit
Same as output
but take a string as argument instead of a byte sequence.
val output_byte : out_channel > int > unit
Write one 8bit integer (as the single character with that code) on the given output channel. The given integer is taken modulo 256.
val output_binary_int : out_channel > int > unit
Write one integer in binary format (4 bytes, bigendian) on the given output channel. The given integer is taken modulo 2^{32}. 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.
val 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.
val seek_out : out_channel > int > unit
seek_out chan pos
sets the current writing position to pos
for channel chan
. This works only for regular files. On files of other kinds (such as terminals, pipes and sockets), the behavior is unspecified.
val pos_out : out_channel > int
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 : 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 : 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 : out_channel > unit
Same as close_out
, but ignore all errors.
val set_binary_mode_out : out_channel > bool > unit
set_binary_mode_out oc true
sets the channel oc
to binary mode: no translations take place during output. set_binary_mode_out oc false
sets the channel oc
to text mode: depending on the operating system, some translations may take place during output. For instance, under Windows, endoflines will be translated from \n
to \r\n
. This function has no effect under operating systems that do not distinguish between text mode and binary mode.
val 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.
val open_in_bin : string > in_channel
val open_in_gen : open_flag list > 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.
val input_char : in_channel > char
Read one character from the given input channel.
End_of_file
if there are no more characters to read.val 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.val 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
.
val 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
.val 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.val input_byte : in_channel > int
Same as input_char
, but return the 8bit integer representing the character.
End_of_file
if an end of file was reached.val input_binary_int : in_channel > int
Read an integer encoded in binary format (4 bytes, bigendian) from the given input channel. See output_binary_int
.
End_of_file
if an end of file was reached while reading the integer.val 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.
val seek_in : in_channel > int > unit
seek_in chan pos
sets the current reading position to pos
for channel chan
. This works only for regular files. On files of other kinds, the behavior is unspecified.
val pos_in : in_channel > int
Return the current reading position for the given channel.
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 endofline 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, endoflines will be translated from \r\n
to \n
. This function has no effect under operating systems that do not distinguish between text mode and binary mode.
module LargeFile: sig .. end
Operations on large files.
type 'a ref = {
mutable contents :

}
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
. Rightassociative 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
.
type ('a, 'b) result =

 Ok of


 Error of

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 ('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.
val format_of_string : ('a, 'b, 'c, 'd, 'e, 'f) format6 > ('a, 'b, 'c, 'd, 'e, 'f) format6
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
. Rightassociative operator, see Ocaml_operators
for more information.
val 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.
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 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 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 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 Spacetime: Spacetime
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
© INRIA 19952020.
https://www.ocaml.org/releases/4.11/htmlman/libref/Stdlib.html