NAME

       Option - Option values.

Module

       Module   Option

Documentation

       Module Option
        : sig end

       Option values.

       Option values explicitly indicate the presence or absence of a value.

       Since 4.08

   Options
       type 'a t = 'a option =
        | None
        | Some of 'a

       The type for option values. Either None or a value Some v .

       val none : 'a option

       none is None .

       val some : 'a -> 'a option

       some v is Some v .

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

       value o ~default is v if o is Some v and default otherwise.

       val get : 'a option -> 'a

       get o is v if o is Some v and

       Raises Invalid_argument otherwise.

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

       bind o f is f v if o is Some v and None if o is None .

       val join : 'a option option -> 'a option

       join oo is Some v if oo is Some (Some v) and None otherwise.

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

       map f o is None if o is None and Some (f v) is o is Some v .

       val fold : none:'a -> some:('b -> 'a) -> 'b option -> 'a

       fold ~none ~some o is none if o is None and some v if o is Some v .

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

       iter f o is f v if o is Some v and () otherwise.

   Predicates and comparisons
       val is_none : 'a option -> bool

       is_none o is true if and only if o is None .

       val is_some : 'a option -> bool

       is_some o is true if and only if o is Some o .

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

       equal  eq  o0 o1 is true if and only if o0 and o1 are both None or if they are Some v0 and
       Some v1 and eq v0 v1 is true .

       val compare : ('a -> 'a -> int) -> 'a option -> 'a option -> int

       compare cmp o0 o1 is a total order on options using cmp to compare values wrapped by  Some
       _ .  None is smaller than Some _ values.

   Converting
       val to_result : none:'e -> 'a option -> ('a, 'e) result

       to_result ~none o is Ok v if o is Some v and Error none otherwise.

       val to_list : 'a option -> 'a list

       to_list o is [] if o is None and [v] if o is Some v .

       val to_seq : 'a option -> 'a Seq.t

       to_seq  o  is  o  as  a  sequence.  None is the empty sequence and Some v is the singleton
       sequence containing v .