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26 lines
501 B
Idris
26 lines
501 B
Idris
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%hide Prelude.integerToNat
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data MyNat : Type where
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Z : MyNat
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S : MyNat -> MyNat
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%builtin Natural MyNat
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integerToMyNat : Integer -> MyNat
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integerToMyNat i = if i <= 0
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then Z
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else S $ integerToMyNat (i - 1)
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%builtin IntegerToNatural integerToMyNat
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natToMyNat : Nat -> MyNat
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natToMyNat Z = Z
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natToMyNat (S k) = S $ natToMyNat k
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%builtin IntegerToNatural natToMyNat
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integerToNotNat : Integer -> Maybe String
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integerToNotNat x = Just "Boo"
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%builtin IntegerToNatural integerToNotNat
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