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oisdk/zipfix.hs

Created July 2, 2018 01:38
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zipfix.hs
zipo :: Functor f => (f (Fix f -> a) -> f (Fix f) -> a) -> Fix f -> Fix f -> a
zipo alg = c where c = (\x -> alg x . unfix) . fmap c . unfix
newtype Fix f = Fix (f (Fix f))
unfix :: Fix f -> f (Fix f)
unfix (Fix f) = f
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