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| Commit | Line | Data |
|---|---|---|
| 64617423 SK |
1 | -module(hope_fun). |
| 2 | ||
| 3 | -export( | |
| 4 | [ id/1 | |
| e033aade | 5 | , curry/1 |
| 0b6ed617 SK |
6 | , compose/1 % alias for compose_right/1 |
| 7 | , compose_right/1 | |
| 8 | , compose_left/1 | |
| cb14ad76 | 9 | , thread/2 |
| 64617423 SK |
10 | ]). |
| 11 | ||
| 12 | -spec id(A) -> | |
| 13 | A. | |
| 14 | id(X) -> | |
| 15 | X. | |
| e033aade SK |
16 | |
| 17 | -spec curry(fun()) -> | |
| 18 | fun(). | |
| 19 | curry(F) -> | |
| a3173cf2 | 20 | {arity, Arity} = erlang:fun_info(F, arity), |
| e033aade SK |
21 | curry(F, [], Arity). |
| 22 | ||
| 23 | -spec curry(fun(), list(), integer()) -> | |
| 24 | fun(). | |
| 25 | curry(F, Args, 0) -> | |
| 26 | apply(F, lists:reverse(Args)); | |
| 27 | curry(F, Args, Arity) -> | |
| 28 | fun (X) -> curry(F, [X | Args], Arity - 1) end. | |
| 0b6ed617 SK |
29 | |
| 30 | -spec compose([fun((A) -> B)]) -> | |
| 31 | fun((A) -> B). | |
| 32 | compose(Fs) -> | |
| 33 | compose_right(Fs). | |
| 34 | ||
| 35 | -spec compose_right([fun((A) -> B)]) -> | |
| 36 | fun((A) -> B). | |
| 37 | compose_right(Fs) -> | |
| 38 | compose_given_fold(Fs, fun lists:foldr/3). | |
| 39 | ||
| 40 | -spec compose_left([fun((A) -> B)]) -> | |
| 41 | fun((A) -> B). | |
| 42 | compose_left(Fs) -> | |
| 43 | compose_given_fold(Fs, fun lists:foldl/3). | |
| 44 | ||
| cb14ad76 SK |
45 | -spec thread([fun((A) -> B)], A) -> |
| 46 | B. | |
| 47 | thread(Fs, X) -> | |
| 48 | F = compose_left(Fs), | |
| 49 | F(X). | |
| 50 | ||
| 0b6ed617 SK |
51 | |
| 52 | %% ============================================================================ | |
| 53 | ||
| 54 | -spec compose_given_fold([fun((A) -> B)], fun((fun((A, B) -> C), B, [A]) -> C)) -> | |
| 55 | fun((A) -> C). | |
| 56 | compose_given_fold(Fs, Fold) -> | |
| 57 | fun (X) -> Fold(fun (F, Y) -> F(Y) end, X, Fs) end. |