| 1 | -module(hope_option). |
| 2 | |
| 3 | |
| 4 | -export_type( |
| 5 | [ t/1 |
| 6 | ]). |
| 7 | |
| 8 | -export( |
| 9 | [ put/2 |
| 10 | , get/2 |
| 11 | , map/2 |
| 12 | , iter/2 |
| 13 | , of_result/1 |
| 14 | ]). |
| 15 | |
| 16 | |
| 17 | -type t(A) :: |
| 18 | none |
| 19 | | {some, A} |
| 20 | . |
| 21 | |
| 22 | |
| 23 | -spec put(A, fun((A) -> boolean())) -> |
| 24 | t(A). |
| 25 | put(X, F) -> |
| 26 | case F(X) |
| 27 | of true -> {some, X} |
| 28 | ; false -> none |
| 29 | end. |
| 30 | |
| 31 | -spec get(t(A), Default :: A) -> |
| 32 | A. |
| 33 | get({some, X}, _) -> X; |
| 34 | get(none , Y) -> Y. |
| 35 | |
| 36 | -spec map(t(A), fun((A) -> (B))) -> |
| 37 | t(B). |
| 38 | map({some, X}, F) -> {some, F(X)}; |
| 39 | map(none , _) -> none. |
| 40 | |
| 41 | -spec iter(t(A), fun((A) -> (ok))) -> |
| 42 | ok. |
| 43 | iter({some, X}, F) -> ok = F(X); |
| 44 | iter(none , _) -> ok. |
| 45 | |
| 46 | -spec of_result(hope_result:t(A, _B)) -> |
| 47 | t(A). |
| 48 | of_result({ok, X}) -> {some, X}; |
| 49 | of_result({error, _}) -> none. |