module Option: Extlib.Option
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.
Author(s): Nicolas Cannasse, David Teller
type'a
t ='a option
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 f None
returns None
.val bind : ('a -> 'b option) -> 'a option -> 'b option
bind f (Some x)
returns f x
and bind f 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
.val get_exn : 'a option -> exn -> 'a
get_exn (Some x) e
returns x
and get_exn None e
raises e
.val enum : 'a option -> 'a Enum.t
enum (Some x)
returns the singleton x
, while enum None
returns
the empty enumerationval of_enum : 'a Enum.t -> 'a option
of_enum e
consumes the first element of e
, if it exists, and
returns Some e
. If e
is empty, return None
exception No_value
get None
.val t_of_sexp : (Sexplib.Sexp.t -> 'a) -> Sexplib.Sexp.t -> 'a t
val sexp_of_t : ('a -> Sexplib.Sexp.t) -> 'a t -> Sexplib.Sexp.t
val print : ('a Extlib.InnerIO.output -> 'b -> unit) ->
'a Extlib.InnerIO.output -> 'b t -> unit
val t_printer : 'a Value_printer.t -> 'a t Value_printer.t
val maybe_printer : 'a Value_printer.t -> 'a t Value_printer.t
module Option.Labels:sig
..end