15 lines
442 B
Haskell
15 lines
442 B
Haskell
module Expression where
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-- The basic unit of the language are Expressions, so we make an
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-- Expression data with the primitive expression values as the
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-- constructors
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data Expression = Number Double
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| Symbol String
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| SExpr [Expression]
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deriving (Eq)
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instance Show Expression where
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show (Number n) = show n
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show (Symbol s) = show s
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show (SExpr es) = "(" ++ unwords (map show es) ++ ")"
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