[hope.git] / src / hope_option.erl

-module(hope_option).

-export_type(
    [ t/1
    ]).

-export(
    [ put/2
    , get/2
    , map/2
    ]).


-type t(A) ::
      none
    | {some, A}
    .


put(X, F) ->
    case F(X)
    of  true  -> {some, X}
    ;   false -> none
    end.


get({some, X}, _) -> X;
get(none     , Y) -> Y.


map({some, X}, F) -> {some, F(X)};
map(none     , _) -> none.
Commit	Line	Data
e492ea13 SK	1	-module(hope_option).
e492ea13 SK	2
3b156801 SK	3	-export_type(
	4	[ t/1
	5	]).
e492ea13	6
3b156801 SK	7	-export(
	8	[ put/2
	9	, get/2
	10	, map/2
	11	]).
e492ea13 SK	12
e492ea13 SK	13
3b156801 SK	14	-type t(A) ::
	15	none
	16	\| {some, A}
	17	.
e492ea13 SK	18
	19
	20	put(X, F) ->
	21	case F(X)
	22	of true -> {some, X}
	23	; false -> none
	24	end.
	25
	26
	27	get({some, X}, _) -> X;
	28	get(none , Y) -> Y.
	29
	30
	31	map({some, X}, F) -> {some, F(X)};
	32	map(none , _) -> none.