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NAME

       Stdlib - The OCaml Standard library.

Module

       Module   Stdlib

Documentation

       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 modules .

   Exceptions
       val raise : exn -> 'a

       Raise the given exception value

       val raise_notrace : exn -> 'a

       A faster version raise which does not record the backtrace.

       Since 4.02.0

       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 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 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 native-code 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 non-blocking I/O channel.

       exception Undefined_recursive_module of (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).

   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.  Left-associative operator, see Ocaml_operators for more information.

       val (<>) : 'a -> 'a -> bool

       Negation of (=) .  Left-associative operator, see Ocaml_operators for more information.

       val (<) : 'a -> 'a -> bool

       See (>=) .  Left-associative operator, see Ocaml_operators for more information.

       val (>) : 'a -> 'a -> bool

       See (>=) .  Left-associative operator,  see Ocaml_operators for more information.

       val (<=) : 'a -> 'a -> bool

       See (>=) .  Left-associative 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 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.

       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  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.

       val (!=) : 'a -> 'a -> bool

       Negation of (==) .  Left-associative operator,  see Ocaml_operators for more information.

   Boolean operations
       val not : bool -> bool

       The boolean negation.

       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.  Right-associative  operator,
       see Ocaml_operators for more information.

       val (&) : bool -> bool -> bool

       Deprecated.

       (&&)  should  be  used  instead.  Right-associative operator, see Ocaml_operators for more
       information.

       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.  Right-associative operator,
       see Ocaml_operators for more information.

       val (or) : bool -> bool -> bool

       Deprecated.

       (||) should be used instead.  Right-associative operator,  see  Ocaml_operators  for  more
       information.

   Debugging
       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".

       Since 4.02.0

       val __FILE__ : string

       __FILE__ returns the name of the file currently being parsed by the compiler.

       Since 4.02.0

       val __LINE__ : int

       __LINE__  returns  the  line number at which this expression appears in the file currently
       being parsed by the compiler.

       Since 4.02.0

       val __MODULE__ : string

       __MODULE__ returns the module name of the file being parsed by the compiler.

       Since 4.02.0

       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.

       Since 4.02.0

       val __FUNCTION__ : string

       __FUNCTION__  returns  the name of the current function or method, including any enclosing
       modules or classes.

       Since 4.12.0

       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".

       Since 4.02.0

       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.

       Since 4.02.0

       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.

       Since 4.02.0

   Composition operators
       val (|>) : '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.

       Since 4.01

       val (@@) : ('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.

       Since 4.01

   Integer arithmetic
       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.

       Since 3.12.0

       val succ : int -> int

       succ x is x + 1 .

       val pred : int -> int

       pred x is x - 1 .

       val (+) : int -> int -> int

       Integer addition.  Left-associative operator, see Ocaml_operators for more information.

       val (-) : int -> int -> int

       Integer   subtraction.    Left-associative   operator,  ,  see  Ocaml_operators  for  more
       information.

       val ( * ) : int -> int -> int

       Integer  multiplication.   Left-associative  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) .
       Left-associative operator, see Ocaml_operators for more information.

       Raises 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 .  Left-associative
       operator, see Ocaml_operators for more information.

       Raises 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.

   Bitwise operations
       val (land) : int -> int -> int

       Bitwise logical and.  Left-associative operator, see Ocaml_operators for more information.

       val (lor) : int -> int -> int

       Bitwise logical or.  Left-associative operator, see Ocaml_operators for more information.

       val (lxor) : int -> int -> int

       Bitwise logical exclusive or.  Left-associative 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 .  Right-associative 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 .
       Right-associative 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  .
       Right-associative operator, see Ocaml_operators for more information.

   Floating-point arithmetic
       OCaml's floating-point numbers follow the IEEE 754 standard, using  double  precision  (64
       bits) numbers.  Floating-point operations never raise an exception on overflow, underflow,
       division by zero, etc.  Instead, special IEEE numbers are returned as appropriate, such as
       infinity  for 1.0 /. 0.0 , neg_infinity for -1.0 /. 0.0 , and nan ('not a number') for 0.0
       /. 0.0 .  These special numbers then  propagate  through  floating-point  computations  as
       expected: for instance, 1.0 /. infinity is 0.0 , basic arithmetic operations ( +.  , -.  ,
       *.  , /.  ) with nan as an argument return nan , ...

       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.

       Since 3.12.0

       val (+.)  : float -> float -> float

       Floating-point  addition.   Left-associative  operator,  see  Ocaml_operators   for   more
       information.

       val (-.)  : float -> float -> float

       Floating-point  subtraction.   Left-associative  operator,  see  Ocaml_operators  for more
       information.

       val ( *. ) : float -> float -> float

       Floating-point multiplication.  Left-associative operator, see  Ocaml_operators  for  more
       information.

       val (/.)  : float -> float -> float

       Floating-point   division.    Left-associative  operator,  see  Ocaml_operators  for  more
       information.

       val ( ** ) : float -> float -> float

       Exponentiation.  Right-associative 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 numerically-accurate results even if x is close  to
       0.0 .

       Since 3.12.0

       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 .

       Since 3.12.0

       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
       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 .

       Since 4.00.0

       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 acosh : float -> float

       Hyperbolic arc cosine.  The argument must fall within the range [1.0, inf] .  Result is in
       radians and is between 0.0 and inf .

       Since 4.13.0

       val asinh : float -> float

       Hyperbolic  arc sine.  The argument and result range over the entire real line.  Result is
       in radians.

       Since 4.13.0

       val atanh : float -> float

       Hyperbolic arc tangent.  The argument must fall within the range [-1.0, 1.0] .  Result  is
       in radians and ranges over the entire real line.

       Since 4.13.0

       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.

       Since 4.00.0

       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 .

       val float : int -> float

       Same as float_of_int .

       val float_of_int : int -> float

       Convert an integer to floating-point.

       val truncate : float -> int

       Same as 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.

       val infinity : float

       Positive infinity.

       val neg_infinity : float

       Negative infinity.

       val 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 .

       val max_float : float

       The largest positive finite value of type float .

       val min_float : 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 =
        | 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.

       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

       String  concatenation.   Right-associative  operator,   see   Ocaml_operators   for   more
       information.

       Raises Invalid_argument if the result is longer then than Sys.max_string_length bytes.

   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.

       Raises Invalid_argument if the argument is outside the range 0--255.

   Unit operations
       val 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.

   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_opt : string -> bool option

       Convert the given string to a boolean.

       Return None if the string is not "true" or "false" .

       Since 4.05

       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 .

       Since 4.05

       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 a string representation of a floating-point number.

       This conversion can involve a loss of precision. For greater control over  the  manner  in
       which the number is printed, see Printf .

       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 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.

       Since 4.05

       val float_of_string : string -> float

       Same as float_of_string_opt , but raise Failure  "float_of_string"  instead  of  returning
       None .

   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 .

       val (@) : 'a list -> 'a list -> 'a list

       List concatenation.  Not tail-recursive (length of the first argument).  Right-associative
       operator, see Ocaml_operators for more information.

   Input/output
       Note: all input/output functions can raise Sys_error when the  system  calls  they  invoke
       fail.

       type in_channel

       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.

   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.

       Since 4.02.0

       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.

       The  conversion  of  the number to a string uses string_of_float and can involve a loss of
       precision.

       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.

       Since 4.02.0

       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.

       The conversion of the number to a string uses string_of_float and can involve  a  loss  of
       precision.

       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.

   Input functions on standard input
       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.

       Raises End_of_file if the end of the file is reached at the beginning of line.

       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.

       Since 4.05

       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
       floating-point number.

       Return None if the line read is not a valid representation of a floating-point number.

       Since 4.05.0

       val read_float : unit -> float

       Same as read_float_opt , but raise Failure "float_of_string" instead of returning None .

   General output functions
       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 .

       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

       Same  as  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 open_out .

       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.

       Since 4.02.0

       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 .

       Raises 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.

       Since 4.02.0

       val 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.

       val 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 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).  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.

       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,  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.

   General input functions
       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

       Same  as  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 open_in .

       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.

       Raises 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.

       Raises 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 .

       Raises End_of_file if the end of file is reached before len characters have been read.

       Raises 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.

       Since 4.02.0

       Raises 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 8-bit integer representing the character.

       Raises End_of_file if the end of file was reached.

       val 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 .

       Raises End_of_file if the 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.  For files opened in text mode
       under Windows, the returned position is approximate (owing to end-of-line conversion);  in
       particular,  saving  the  current  position with pos_in , then going back to this position
       using seek_in will not work.  For this programming idiom to work  reliably  and  portably,
       the file must be opened in binary mode.

       val in_channel_length : in_channel -> int

       Return  the  size (number of characters) of the regular file on which the given channel is
       opened.  If the channel is opened on a file that is not a  regular  file,  the  result  is
       meaningless.   The  returned  size does not take into account the end-of-line translations
       that can be performed when reading from a channel opened in text mode.

       val close_in : in_channel -> unit

       Close the given channel.  Input functions  raise  a  Sys_error  exception  when  they  are
       applied to a closed input channel, except close_in , which does nothing when applied to an
       already closed channel.

       val close_in_noerr : in_channel -> unit

       Same as close_in , but ignore all errors.

       val set_binary_mode_in : in_channel -> bool -> unit

       set_binary_mode_in ic true sets the channel ic to binary mode: no translations take  place
       during input.  set_binary_mode_out ic false sets the channel ic to text mode: depending on
       the operating system, some translations may take place during input.  For instance,  under
       Windows,  end-of-lines  will  be translated from \r\n to \n .  This function has no effect
       under operating systems that do not distinguish between text mode and binary mode.

   Operations on large files
       module LargeFile : sig end

       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 = {

       mutable contents : 'a ;
        }

       The type of references (mutable indirection cells) containing a value of type 'a .

       val ref : 'a -> 'a ref

       Return a fresh reference containing the given value.

       val (!)  : 'a ref -> 'a

       !r  returns  the  current  contents  of reference r .  Equivalent to fun r -> r.contents .
       Unary operator, see Ocaml_operators for more information.

       val (:=) : 'a ref -> 'a -> unit

       r := a stores the value of a in reference r .  Equivalent to fun r v -> r.contents <- v  .
       Right-associative operator, see Ocaml_operators for more information.

       val incr : int ref -> unit

       Increment  the integer contained in the given reference.  Equivalent to fun r -> r := succ
       !r .

       val decr : int ref -> unit

       Decrement the integer contained in the given reference.  Equivalent to fun r -> r :=  pred
       !r .

   Result type
       type ('a, 'b) result =
        | Ok of 'a
        | Error of 'b

       Since 4.03.0

   Operations on format strings
       Format  strings  are  character  strings with special lexical conventions that defines the
       functionality of formatted input/output functions. Format strings are used  to  read  data
       with  formatted  input functions from module Scanf and to print data with formatted output
       functions from modules Printf and Format .

       Format strings are made of three kinds of entities:

       -conversions specifications, introduced by the special character '%' followed  by  one  or
       more characters specifying what kind of argument to read or print,

       -formatting  indications,  introduced by the special character '@' followed by one or more
       characters specifying how to read or print the argument,

       -plain characters that are  regular  characters  with  usual  lexical  conventions.  Plain
       characters specify string literals to be read in the input or printed in the output.

       There is an additional lexical rule to escape the special characters '%' and '@' in format
       strings: if a special character follows  a  '%'  character,  it  is  treated  as  a  plain
       character. In other words, "%%" is considered as a plain '%' and "%@" as a plain '@' .

       For more information about conversion specifications and formatting indications available,
       read the documentation of modules Scanf , Printf and Format .

       Format strings have a general and highly polymorphic type ('a, 'b, 'c, 'd, 'e, 'f) format6
       .   The  two  simplified  types,  format  and  format4  below  are  included  for backward
       compatibility with earlier releases of OCaml.

       The meaning of format string type parameters is as follows:

       - 'a is the type of the parameters of the format for formatted output functions  (  printf
       -style  functions);  'a  is  the type of the values read by the format for formatted input
       functions ( scanf -style functions).

       - 'b is the type of input source for formatted input functions  and  the  type  of  output
       target  for  formatted output functions.  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 .  Right-associative operator, see  Ocaml_operators
       for more information.

   Program termination
       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:

       -executes exit

       -terminates, either normally or because of an uncaught exception

       -executes the C function caml_shutdown .  The functions are called in 'last in, first out'
       order: the function most recently added with at_exit is called first.

   Standard library modules
       module Arg : (module Stdlib__Arg)

       module Array : (module Stdlib__Array)

       module ArrayLabels : (module Stdlib__ArrayLabels)

       module Atomic : (module Stdlib__Atomic)

       module Bigarray : (module Stdlib__Bigarray)

       module Bool : (module Stdlib__Bool)

       module Buffer : (module Stdlib__Buffer)

       module Bytes : (module Stdlib__Bytes)

       module BytesLabels : (module Stdlib__BytesLabels)

       module Callback : (module Stdlib__Callback)

       module Char : (module Stdlib__Char)

       module Complex : (module Stdlib__Complex)

       module Digest : (module Stdlib__Digest)

       module Either : (module Stdlib__Either)

       module Ephemeron : (module Stdlib__Ephemeron)

       module Filename : (module Stdlib__Filename)

       module Float : (module Stdlib__Float)

       module Format : (module Stdlib__Format)

       module Fun : (module Stdlib__Fun)

       module Gc : (module Stdlib__Gc)

       module Genlex : (module Stdlib__Genlex)

       module Hashtbl : (module Stdlib__Hashtbl)

       module In_channel : (module Stdlib__In_channel)

       module Int : (module Stdlib__Int)

       module Int32 : (module Stdlib__Int32)

       module Int64 : (module Stdlib__Int64)

       module Lazy : (module Stdlib__Lazy)

       module Lexing : (module Stdlib__Lexing)

       module List : (module Stdlib__List)

       module ListLabels : (module Stdlib__ListLabels)

       module Map : (module Stdlib__Map)

       module Marshal : (module Stdlib__Marshal)

       module MoreLabels : (module Stdlib__MoreLabels)

       module Nativeint : (module Stdlib__Nativeint)

       module Obj : (module Stdlib__Obj)

       module Oo : (module Stdlib__Oo)

       module Option : (module Stdlib__Option)

       module Out_channel : (module Stdlib__Out_channel)

       module Parsing : (module Stdlib__Parsing)

       module Pervasives : (module Stdlib__Pervasives)

       module Printexc : (module Stdlib__Printexc)

       module Printf : (module Stdlib__Printf)

       module Queue : (module Stdlib__Queue)

       module Random : (module Stdlib__Random)

       module Result : (module Stdlib__Result)

       module Scanf : (module Stdlib__Scanf)

       module Seq : (module Stdlib__Seq)

       module Set : (module Stdlib__Set)

       module Stack : (module Stdlib__Stack)

       module StdLabels : (module Stdlib__StdLabels)

       module Stream : (module Stdlib__Stream)

       module String : (module Stdlib__String)

       module StringLabels : (module Stdlib__StringLabels)

       module Sys : (module Stdlib__Sys)

       module Uchar : (module Stdlib__Uchar)

       module Unit : (module Stdlib__Unit)

       module Weak : (module Stdlib__Weak)