2019-07-27 19:01:02 +03:00
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import Data.Fin
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import Data.Vect
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tail : {0 A : Type} -> {n : Nat} -> (Fin (S n) -> A) -> (Fin n -> A)
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tail f = f . FS
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toVect : {0 A : Type} -> {n : Nat} -> (Fin n -> A) -> Vect n A
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toVect {n = Z} _ = Nil
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toVect {n = S m} f = (f FZ) :: (toVect (tail f))
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record Iso a b where
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constructor MkIso
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to : a -> b
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from : b -> a
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toFrom : (y : b) -> to (from y) = y
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fromTo : (x : a) -> from (to x) = x
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interface Finite t where
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card : Nat
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2019-10-26 00:24:25 +03:00
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iso : Iso t (Fin card)
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2019-07-27 19:01:02 +03:00
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-- default methods
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foo : Vect card t
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foo = toVect (from iso)
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