[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
2a40de4f	3
3b156801 SK	4	-export_type(
	5	[ t/1
	6	]).
e492ea13	7
3b156801 SK	8	-export(
	9	[ put/2
	10	, get/2
	11	, map/2
	12	]).
e492ea13 SK	13
e492ea13 SK	14
3b156801 SK	15	-type t(A) ::
	16	none
	17	\| {some, A}
	18	.
e492ea13 SK	19
	20
	21	put(X, F) ->
	22	case F(X)
	23	of true -> {some, X}
	24	; false -> none
	25	end.
	26
e492ea13 SK	27	get({some, X}, _) -> X;
	28	get(none , Y) -> Y.
	29
e492ea13 SK	30	map({some, X}, F) -> {some, F(X)};
e492ea13 SK	31	map(none , _) -> none.