Commit | Line | Data |
---|---|---|
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 | ]). | |
13 | ||
14 | ||
15 | -type t(A) :: | |
16 | none | |
17 | | {some, A} | |
18 | . | |
19 | ||
20 | ||
21 | put(X, F) -> | |
22 | case F(X) | |
23 | of true -> {some, X} | |
24 | ; false -> none | |
25 | end. | |
26 | ||
27 | get({some, X}, _) -> X; | |
28 | get(none , Y) -> Y. | |
29 | ||
30 | map({some, X}, F) -> {some, F(X)}; | |
31 | map(none , _) -> none. |