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anton-trunov/MutuallyInductiveTypesViaTypeFamilies.idr

Created February 10, 2017 15:32
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MutuallyInductiveTypesViaTypeFamilies.idr
%default total
data FS : (switch : Bool) -> Type where
FirstSimple : FS False
FirstSecond : FS True -> FS False
SecondSimple : FS True
SecondFirst : List (FS False) -> FS True
calculate : FS b -> Nat
calculate FirstSimple = 1
calculate (FirstSecond x) = calculate x
calculate SecondSimple = 2
calculate (SecondFirst xs) = foldl (\acc, x => acc + calculate x) 0 xs
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