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Sophia-Gold/Iterate.hs

Created April 6, 2018 09:56
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type level iterate
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Iterate.hs
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE KindSignatures #-}
data Nat = Z | S Nat
type family Iterate (n :: Nat) f a where
Iterate Z f a = a
Iterate (S n) f a = f (Iterate n f a)
thing :: Iterate (S (S (S Z))) [] Int
thing = [[[3,4],[2]],[[],[9,9,9]],[]]
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