Commit | Line | Data |
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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 | |
12 | ]). | |
e492ea13 SK |
13 | |
14 | ||
3b156801 SK |
15 | -type t(A) :: |
16 | none | |
17 | | {some, A} | |
18 | . | |
e492ea13 SK |
19 | |
20 | ||
ed9905af SK |
21 | -spec put(A, fun((A) -> boolean())) -> |
22 | t(A). | |
e492ea13 SK |
23 | put(X, F) -> |
24 | case F(X) | |
25 | of true -> {some, X} | |
26 | ; false -> none | |
27 | end. | |
28 | ||
ed9905af SK |
29 | -spec get(t(A), Default :: A) -> |
30 | A. | |
e492ea13 SK |
31 | get({some, X}, _) -> X; |
32 | get(none , Y) -> Y. | |
33 | ||
ed9905af SK |
34 | -spec map(t(A), fun((A) -> (B))) -> |
35 | t(B). | |
e492ea13 SK |
36 | map({some, X}, F) -> {some, F(X)}; |
37 | map(none , _) -> none. |