package extlib

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Functions for the option type.

Options are an Ocaml standard type that can be either None (undefined) or Some x where x can be any value. Options are widely used in Ocaml to represent undefined values (a little like NULL in C, but in a type and memory safe way). This module adds some functions for working with options.

val may : ('a -> unit) -> 'a option -> unit

may f (Some x) calls f x and may f None does nothing.

val map : ('a -> 'b) -> 'a option -> 'b option

map f (Some x) returns Some (f x) and map None returns None.

val default : 'a -> 'a option -> 'a

default x (Some v) returns v and default x None returns x.

val map_default : ('a -> 'b) -> 'b -> 'a option -> 'b

map_default f x (Some v) returns f v and map_default f x None returns x.

val is_none : 'a option -> bool

is_none None returns true otherwise it returns false.

val is_some : 'a option -> bool

is_some (Some x) returns true otherwise it returns false.

val get : 'a option -> 'a

get (Some x) returns x and get None raises No_value.

exception No_value

Raised when calling get None.


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