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e492ea13 SK |
1 | -module(hope_option). |
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 | |
27a4f25f | 12 | , iter/2 |
2497062c | 13 | , of_result/1 |
3b156801 | 14 | ]). |
e492ea13 SK |
15 | |
16 | ||
3b156801 SK |
17 | -type t(A) :: |
18 | none | |
19 | | {some, A} | |
20 | . | |
e492ea13 SK |
21 | |
22 | ||
ed9905af SK |
23 | -spec put(A, fun((A) -> boolean())) -> |
24 | t(A). | |
e492ea13 SK |
25 | put(X, F) -> |
26 | case F(X) | |
27 | of true -> {some, X} | |
28 | ; false -> none | |
29 | end. | |
30 | ||
ed9905af SK |
31 | -spec get(t(A), Default :: A) -> |
32 | A. | |
e492ea13 SK |
33 | get({some, X}, _) -> X; |
34 | get(none , Y) -> Y. | |
35 | ||
ed9905af SK |
36 | -spec map(t(A), fun((A) -> (B))) -> |
37 | t(B). | |
e492ea13 SK |
38 | map({some, X}, F) -> {some, F(X)}; |
39 | map(none , _) -> none. | |
27a4f25f SK |
40 | |
41 | -spec iter(t(A), fun((A) -> (ok))) -> | |
42 | ok. | |
43 | iter({some, X}, F) -> ok = F(X); | |
44 | iter(none , _) -> ok. | |
2497062c SK |
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. |