58 lines
1.2 KiB
Haskell
58 lines
1.2 KiB
Haskell
{-# Language TemplateHaskell, QuasiQuotes, FlexibleContexts #-}
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import Text.Peggy hiding (space)
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import AST
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[peggy|
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top :: [AST] = statements !.
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lineComment :: () = '--' (!'\n' .)* '\n' { () }
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space :: () = [ \r\n\t] { () } / lineComment
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statements :: [AST]
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= statement+
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statement :: AST
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= expr "."
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args :: AST
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= expr ("," expr)+ { TupleConst ($1 : $2) }
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/ expr? { case $1 of
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Just x -> x
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Nothing -> UnitConst }
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pattern :: Pattern
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= integer { IntP $1 }
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funpattern :: Pattern
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= pattern ("," pattern)+ { TupleP ($1 : $2) }
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/ pattern? { case $1 of
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Just x -> x
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Nothing -> UnitP }
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expr :: AST
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= expr "(" args ")" { Call $1 $2 }
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/ expr "+" fact { Add $1 $2 }
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/ expr "-" fact { Sub $1 $2 }
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/ identifier "(" funpattern ")" "->" expr { Defun $1 (Lambda [($2, $3)]) }
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/ fact
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fact :: AST
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= fact "*" term { Mul $1 $2 }
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/ fact "/" term { Div $1 $2 }
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/ term
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term :: AST
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= "(" expr ")"
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/ integer { IntConst $1 }
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/ identifier { Var $1 }
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identifier ::: String
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= [a-zA-Z_] [a-zA-Z0-9_'?!]* { $1 : $2 }
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integer ::: Integer
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= [1-9] [0-9]* { read ($1 : $2) }
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|]
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main :: IO ()
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main = print . parseString top "<stdin>" =<< getContents |