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kseo/Fold.hs

Created March 7, 2016 02:13
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fold and Monoid
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Fold.hs
import Prelude hiding (foldr)
import Data.Monoid
foldComposing :: (a -> (b -> b)) -> [a] -> Endo b
foldComposing f = foldMap (Endo . f)
foldr :: (a -> (b -> b)) -> b -> [a] -> b
foldr f z xs = appEndo (foldComposing f xs) z
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