package containers

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package containers
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Options

type +'a t = 'a option
val map : ('a -> 'b) -> 'a t -> 'b t

Transform the element inside, if any

val maybe : ('a -> 'b) -> 'b -> 'a t -> 'b

maybe f x o is x if o is None, otherwise it's f y if o = Some y

val is_some : _ t -> bool
val compare : ('a -> 'a -> int) -> 'a t -> 'a t -> int
val equal : ('a -> 'a -> bool) -> 'a t -> 'a t -> bool
val return : 'a -> 'a t

Monadic return

val (>|=) : 'a t -> ('a -> 'b) -> 'b t

Infix version of map

val (>>=) : 'a t -> ('a -> 'b t) -> 'b t

Monadic bind

val flat_map : ('a -> 'b t) -> 'a t -> 'b t

Flip version of >>=

val map2 : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
val iter : ('a -> unit) -> 'a t -> unit

Iterate on 0 or 1 elements

val fold : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a

Fold on 0 or 1 elements

val filter : ('a -> bool) -> 'a t -> 'a t

Filter on 0 or 1 elements

  • since 0.5
val get : 'a -> 'a t -> 'a

get default x unwraps x, but if x = None it returns default instead.

  • since 0.4.1
val get_exn : 'a t -> 'a

Open the option, possibly failing if it is None

  • raises Invalid_argument

    if the option is None

val get_lazy : (unit -> 'a) -> 'a t -> 'a

get_lazy default_fn x unwraps x, but if x = None it returns default_fn () instead.

  • since 0.6.1
val sequence_l : 'a t list -> 'a list t

sequence_l [x1; x2; ...; xn] returns Some [y1;y2;...;yn] if every xi is Some yi. Otherwise, if the list contains at least one None, the result is None.

val wrap : ?handler:(exn -> bool) -> ('a -> 'b) -> 'a -> 'b option

wrap f x calls f x and returns Some y if f x = y. If f x raises any exception, the result is None. This can be useful to wrap functions such as Map.S.find.

  • parameter handler

    the exception handler, which returns true if the exception is to be caught.

val wrap2 : ?handler:(exn -> bool) -> ('a -> 'b -> 'c) -> 'a -> 'b -> 'c option

wrap2 f x y is similar to wrap1 but for binary functions.

Applicative

val pure : 'a -> 'a t

Alias to return

val (<*>) : ('a -> 'b) t -> 'a t -> 'b t
val (<$>) : ('a -> 'b) -> 'a t -> 'b t

Alternatives

val (<+>) : 'a t -> 'a t -> 'a t

a <+> b is a if a is Some _, b otherwise

val choice : 'a t list -> 'a t

choice returns the first non-None element of the list, or None

Conversion and IO

val to_list : 'a t -> 'a list
val of_list : 'a list -> 'a t

Head of list, or None

type 'a sequence = ('a -> unit) -> unit
type 'a gen = unit -> 'a option
type 'a printer = Buffer.t -> 'a -> unit
type 'a random_gen = Random.State.t -> 'a
val random : 'a random_gen -> 'a t random_gen
val to_gen : 'a t -> 'a gen
val to_seq : 'a t -> 'a sequence
val pp : 'a printer -> 'a t printer