17 lines
433 B
Haskell
17 lines
433 B
Haskell
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{-# LANGUAGE InstanceSigs #-}
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module Terms where
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-- Lambda-Terms
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data Term
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= Var String
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| App Term Term
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| Abs String Term
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deriving (Eq, Ord)
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instance Show Term where
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show :: Term -> String
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show (Var x) = x
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show (App t1 t2) = show t1 ++ " " ++ go t2
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where
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go (App t3 t4) = "(" ++ show t3 ++ " " ++ go t4 ++ ")"
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go t = show t
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show (Abs x t) = "\\" ++ x ++ ". " ++ show t
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