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

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

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

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

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

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

See Stdlib.(>=). 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 Stdlib.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 Stdlib.(==). 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

    Stdlib.(&&) 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

    Stdlib.(||) 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 2Sys.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 t