package containers

  1. Overview
  2. Docs
package containers
Legend:
Library
Module
Module type
Parameter
Class
Class type

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 map_or : default:'b -> ('a -> 'b) -> 'a t -> 'b

map_or ~default f o is f x if o = Some x, default otherwise

  • since 0.16
val is_some : _ t -> bool
val is_none : _ t -> bool
  • since 0.11
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, that is return x = Some x

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 element

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

Fold on 0 or 1 element

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

Filter on 0 or 1 element

  • since 0.5
val if_ : ('a -> bool) -> 'a -> 'a option

if_ f x is Some x if f x, None otherwise

  • since 0.17
val exists : ('a -> bool) -> 'a t -> bool
  • since 0.17
val for_all : ('a -> bool) -> 'a t -> bool
  • since 0.17
val get : 'a -> 'a t -> 'a

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

  • since 0.4.1
  • deprecated

    use get_or

    @since 0.18

val get_or : default:'a -> 'a t -> 'a

get_or ~default o extracts the value from o, or returns default if o = None.

  • since 0.18
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

Infix Operators

  • since 0.16
module Infix : sig ... end

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 fmt = Format.formatter -> 'a -> unit
type 'a random_gen = Random.State.t -> 'a
val random : 'a random_gen -> 'a t random_gen
val choice_seq : 'a t sequence -> 'a t

choice_seq s is similar to choice, but works on sequences. It returns the first Some x occurring in s, or None otherwise.

  • since 0.13
val to_gen : 'a t -> 'a gen
val to_seq : 'a t -> 'a sequence
val pp : 'a printer -> 'a t printer
val print : 'a fmt -> 'a t fmt
  • since 0.13