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Fix Filter to not take exponential time

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Lysxia 2020-01-06 05:13:31 -05:00
parent e6949099c3
commit 4113cb1607
1 changed files with 3 additions and 3 deletions
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6
src/Fcf/Data/List.hs
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@ -100,9 +100,9 @@ type instance Eval (ConcatMap f lst) = Eval (Concat (Eval (Map f lst)))
data Filter :: (a -> Exp Bool) -> [a] -> Exp [a]
type instance Eval (Filter _p '[]) = '[]
type instance Eval (Filter p (a ': as)) =
If (Eval (p a))
(a ': Eval (Filter p as))
(Eval (Filter p as))
Eval (If (Eval (p a))
('(:) a <$> Filter p as)
(Filter p as))
data Head :: [a] -> Exp (Maybe a)
type instance Eval (Head '[]) = 'Nothing