Commit | Line | Data |
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e492ea13 SK |
1 | -module(hope_option). |
2 | ||
b69220d7 | 3 | -behavior(hope_gen_monad). |
2a40de4f | 4 | |
3b156801 SK |
5 | -export_type( |
6 | [ t/1 | |
7 | ]). | |
e492ea13 | 8 | |
3b156801 SK |
9 | -export( |
10 | [ put/2 | |
11 | , get/2 | |
4af0774b | 12 | , return/1 |
9a5e47fa | 13 | , return/2 |
3b156801 | 14 | , map/2 |
27a4f25f | 15 | , iter/2 |
4af0774b | 16 | , pipe/2 |
2497062c | 17 | , of_result/1 |
f2e1fffc | 18 | , of_undefined/1 |
3b156801 | 19 | ]). |
e492ea13 SK |
20 | |
21 | ||
3b156801 SK |
22 | -type t(A) :: |
23 | none | |
24 | | {some, A} | |
25 | . | |
e492ea13 SK |
26 | |
27 | ||
ed9905af SK |
28 | -spec put(A, fun((A) -> boolean())) -> |
29 | t(A). | |
e492ea13 | 30 | put(X, F) -> |
9a5e47fa | 31 | return(X, F). |
e492ea13 | 32 | |
ed9905af SK |
33 | -spec get(t(A), Default :: A) -> |
34 | A. | |
e492ea13 SK |
35 | get({some, X}, _) -> X; |
36 | get(none , Y) -> Y. | |
37 | ||
4af0774b SK |
38 | -spec return(A) -> |
39 | {some, A}. | |
40 | return(X) -> | |
41 | {some, X}. | |
42 | ||
9a5e47fa SK |
43 | -spec return(A, fun((A) -> boolean())) -> |
44 | t(A). | |
45 | return(X, Condition) -> | |
46 | case Condition(X) | |
47 | of true -> {some, X} | |
48 | ; false -> none | |
49 | end. | |
50 | ||
ed9905af SK |
51 | -spec map(t(A), fun((A) -> (B))) -> |
52 | t(B). | |
e492ea13 SK |
53 | map({some, X}, F) -> {some, F(X)}; |
54 | map(none , _) -> none. | |
27a4f25f SK |
55 | |
56 | -spec iter(t(A), fun((A) -> (ok))) -> | |
57 | ok. | |
58 | iter({some, X}, F) -> ok = F(X); | |
59 | iter(none , _) -> ok. | |
2497062c | 60 | |
4af0774b SK |
61 | -spec pipe([fun((A) -> t(B))], A) -> |
62 | t(B). | |
63 | pipe([], X) -> | |
64 | return(X); | |
65 | pipe([F|Fs], X) -> | |
66 | case F(X) | |
67 | of none -> none | |
68 | ; {some, Y} -> pipe(Fs, Y) | |
69 | end. | |
70 | ||
2497062c SK |
71 | -spec of_result(hope_result:t(A, _B)) -> |
72 | t(A). | |
73 | of_result({ok, X}) -> {some, X}; | |
74 | of_result({error, _}) -> none. | |
f2e1fffc SK |
75 | |
76 | -spec of_undefined(undefined | A) -> | |
77 | t(A). | |
78 | of_undefined(undefined) -> none; | |
79 | of_undefined(X) -> {some, X}. |