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10 lines
230 B
Idris
10 lines
230 B
Idris
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data Mu : (f : Type -> Type) -> Type where
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MkMu : f (Mu f) -> Mu f
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%spec a, f, fun
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fold : (fun : Functor f) => (f a -> a) -> Mu f -> a
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fold alg (MkMu t) = alg (fold {a, f, fun} alg <$> t)
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size : Mu List -> Nat
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size = fold sum
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