mirror of
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233 lines
7.9 KiB
OCaml
233 lines
7.9 KiB
OCaml
(* This file is free software, part of containers. See file "license" for more details. *)
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(** {1 Options} *)
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type +'a t = 'a option
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val map : ('a -> 'b) -> 'a t -> 'b t
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(** [map f o] applies the function [f] to the element inside [o], if any. *)
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val map_or : default:'b -> ('a -> 'b) -> 'a t -> 'b
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(** [map_or ~default f o] is [f x] if [o = Some x], [default] otherwise.
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@since 0.16 *)
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val map_lazy : (unit -> 'b) -> ('a -> 'b) -> 'a t -> 'b
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(** [map_lazy default_fn f o] if [f o] if [o = Some x], [default_fn ()] otherwise.
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@since 1.2 *)
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val is_some : _ t -> bool
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(** [is_some (Some x)] returns [true] otherwise it returns [false]. *)
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val is_none : _ t -> bool
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(** [is_none None] returns [true] otherwise it returns [false].
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@since 0.11 *)
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val compare : ('a -> 'a -> int) -> 'a t -> 'a t -> int
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(** [compare comp o1 o2] compares two options [o1] and [o2],
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using custom comparators [comp] for the value.
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[None] is always assumed to be less than [Some _]. *)
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val equal : ('a -> 'a -> bool) -> 'a t -> 'a t -> bool
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(** [equal p o1 o2] tests for equality between option types [o1] and [o2],
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using a custom equality predicate [p]. *)
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val return : 'a -> 'a t
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(** [return x] is a monadic return, that is [return x = Some x]. *)
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val (>|=) : 'a t -> ('a -> 'b) -> 'b t
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(** [o >|= f] is the infix version of {!map}. *)
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val flat_map : ('a -> 'b t) -> 'a t -> 'b t
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(** [flat_map f o] is equivalent to {!map} followed by {!flatten}.
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Flip version of {!>>=}. *)
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val bind : 'a t -> ('a -> 'b t) -> 'b t
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(** [bind o f] is [f v] if [o] is [Some v], [None] otherwise.
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Monadic bind.
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@since NEXT_RELEASE *)
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val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
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(** [o >>= f] is the infix version of {!bind}. *)
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val map2 : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
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(** [map2 f o1 o2] maps ['a option] and ['b option] to a ['c option] using [f]. *)
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val iter : ('a -> unit) -> 'a t -> unit
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(** [iter f o] applies [f] to [o]. Iterate on 0 or 1 element. *)
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val fold : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
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(** [fold f init o] is [f init x] if [o] is [Some x], or [init] if [o] is [None].
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Fold on 0 or 1 element. *)
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val filter : ('a -> bool) -> 'a t -> 'a t
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(** [filter f o] returns [Some x] if [f (Some x)] is [true],
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or [None] if [f (Some x)] is [false] or if [o] is [None].
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Filter on 0 or 1 element.
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@since 0.5 *)
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val if_ : ('a -> bool) -> 'a -> 'a option
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(** [if_ f x] is [Some x] if [f x], [None] otherwise.
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@since 0.17 *)
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val exists : ('a -> bool) -> 'a t -> bool
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(** [exists f o] returns [true] iff there exists an element for which
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the provided function [f] evaluates to [true].
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@since 0.17 *)
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val for_all : ('a -> bool) -> 'a t -> bool
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(** [for_all f o] returns [true] iff the provided function [f] evaluates to [true] for all elements.
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@since 0.17 *)
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val get_or : default:'a -> 'a t -> 'a
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(** [get_or ~default o] extracts the value from [o], or
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returns [default] if [o] is [None].
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@since 0.18 *)
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val value : 'a t -> default:'a -> 'a
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(** [value o ~default] is similar to the Stdlib's [Option.value] and to {!get_or}.
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@since 2.8 *)
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val get_exn : 'a t -> 'a
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(** [get_exn o] returns [x] if [o] is [Some x] or fails if [o] is [None].
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@raise Invalid_argument if the option is [None]. *)
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val get_lazy : (unit -> 'a) -> 'a t -> 'a
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(** [get_lazy default_fn o] unwraps [o], but if [o] is [None] it returns [default_fn ()] instead.
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@since 0.6.1 *)
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val sequence_l : 'a t list -> 'a list t
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(** [sequence_l [x1; x2; …; xn]] returns [Some [y1; y2; …; yn]] if
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every [xi] is [Some yi]. Otherwise, if the list contains at least
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one [None], the result is [None]. *)
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val wrap : ?handler:(exn -> bool) -> ('a -> 'b) -> 'a -> 'b option
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(** [wrap ?handler f x] calls [f x] and returns [Some y] if [f x = y]. If [f x] raises
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any exception, the result is [None]. This can be useful to wrap functions
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such as [Map.S.find].
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@param handler the exception handler, which returns [true] if the
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exception is to be caught. *)
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val wrap2 : ?handler:(exn -> bool) -> ('a -> 'b -> 'c) -> 'a -> 'b -> 'c option
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(** [wrap2 ?handler f x y] is similar to {!wrap} but for binary functions. *)
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(** {2 Applicative} *)
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val pure : 'a -> 'a t
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(** [pure x] is an alias to {!return}. *)
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val (<*>) : ('a -> 'b) t -> 'a t -> 'b t
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(** [f <*> (Some x)] returns [Some (f x)] and [f <*> None] returns [None]. *)
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val (<$>) : ('a -> 'b) -> 'a t -> 'b t
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(** [f <$> o] is like [map f o]. *)
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(** {2 Alternatives} *)
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val or_ : else_:('a t) -> 'a t -> 'a t
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(** [or_ ~else_ o] is [o] if [o] is [Some _], [else_] if [o] is [None].
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@since 1.2 *)
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val or_lazy : else_:(unit -> 'a t) -> 'a t -> 'a t
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(** [or_lazy ~else_ o] is [o] if [o] is [Some _], [else_ ()] if [o] is [None].
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@since 1.2 *)
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val (<+>) : 'a t -> 'a t -> 'a t
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(** [o1 <+> o2] is [o1] if [o1] is [Some _], [o2] if [o1] is [None]. *)
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val choice : 'a t list -> 'a t
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(** [choice lo] returns the first non-[None] element of the list [lo], or [None]. *)
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val flatten : 'a t t -> 'a t
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(** [flatten oo] transforms [Some x] into [x].
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@since 2.2 *)
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val return_if : bool -> 'a -> 'a t
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(** [return_if b x] applies [Some] or [None] depending on the boolean [b].
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More precisely, [return_if false x] is [None],
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and [return_if true x] is [Some x].
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@since 2.2 *)
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(** {2 Infix Operators}
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@since 0.16 *)
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module Infix : sig
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val (>|=) : 'a t -> ('a -> 'b) -> 'b t
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(** [o >|= f] is [map f o]. *)
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val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
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(** [o >>= f] is the monadic bind. *)
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val (<*>) : ('a -> 'b) t -> 'a t -> 'b t
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(** [f <*> o] returns [Some (f x)] if [o] is [Some x] and [None] if [o] is [None]. *)
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val (<$>) : ('a -> 'b) -> 'a t -> 'b t
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(** [f <$> o] is like [map f o]. *)
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val (<+>) : 'a t -> 'a t -> 'a t
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(** [o1 <+> o2] is [o1] if [o1] is [Some _], [o2] if [o1] is [None]. *)
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(** Let operators on OCaml >= 4.08.0, nothing otherwise
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@since 2.8 *)
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include CCShimsMkLet_.S with type 'a t_let := 'a option
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end
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(** Let operators on OCaml >= 4.08.0, nothing otherwise
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@since 2.8 *)
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include CCShimsMkLet_.S with type 'a t_let := 'a option
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(** {2 Conversion and IO} *)
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val to_list : 'a t -> 'a list
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(** [to_list o] returns [[x]] if [o] is [Some x] or the empty list [[]] if [o] is [None]. *)
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val of_list : 'a list -> 'a t
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(** [of_list l] returns [Some x] (x being the head of the list l), or [None] if [l] is the empty list. *)
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val to_result : 'e -> 'a t -> ('a, 'e) result
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(** [to_result e o] returns [Ok x] if [o] is [Some x], or [Error e] if [o] is [None].
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@since 1.2 *)
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val to_result_lazy : (unit -> 'e) -> 'a t -> ('a, 'e) result
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(** [to_result_lazy f o] returns [Ok x] if [o] is [Some x] or [Error f] if [o] is [None].
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@since 1.2 *)
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val of_result : ('a, _) result -> 'a t
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(** [of_result result] returns an option from a [result].
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@since 1.2 *)
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type 'a iter = ('a -> unit) -> unit
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type 'a gen = unit -> 'a option
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type 'a printer = Format.formatter -> 'a -> unit
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type 'a random_gen = Random.State.t -> 'a
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val random : 'a random_gen -> 'a t random_gen
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val choice_iter : 'a t iter -> 'a t
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(** [choice_iter iter] is similar to {!choice}, but works on [iter].
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It returns the first [Some x] occurring in [iter], or [None] otherwise.
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@since 3.0 *)
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val choice_seq : 'a t Seq.t -> 'a t
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(** [choice_seq seq] works on [Seq.t].
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It returns the first [Some x] occurring in [seq], or [None] otherwise.
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@since 3.0 *)
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val to_gen : 'a t -> 'a gen
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(** [to_gen o] is [o] as a [gen]. [Some x] is the singleton [gen] containing [x]
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and [None] is the empty [gen]. *)
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val to_seq : 'a t -> 'a Seq.t
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(** [to_seq o] is [o] as a sequence [Seq.t]. [Some x] is the singleton sequence containing [x]
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and [None] is the empty sequence.
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Same as {!Stdlib.Option.to_seq}
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Renamed from [to_std_seq] since NEXT_RELEASE.
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@since NEXT_RELEASE *)
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val to_iter : 'a t -> 'a iter
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(** [to_iter o] returns an internal iterator, like in the library [Iter].
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@since 2.8 *)
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val pp : 'a printer -> 'a t printer
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(** [pp ppf o] pretty-prints option [o] using [ppf]. *)
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