mirror of https://github.com/sharkdp/bat.git
87 lines
1.9 KiB
Haskell
87 lines
1.9 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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-- simple parser for a Lisp-like syntax I wrote some time ago
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import Data.Void (Void)
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import Data.Text (Text)
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import qualified Data.Text as T
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import Text.Megaparsec.Char
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import Text.Megaparsec.Error (errorBundlePretty)
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import Text.Megaparsec hiding (State)
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import qualified Text.Megaparsec.Char.Lexer as L
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data LispVal
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= Symbol Text
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| List [LispVal]
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| Number Integer
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| String Text
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| LispTrue
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| LispFalse
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| Nil
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deriving (Show, Eq)
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type Parser = Parsec Void Text
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readStr :: Text -> Either String [LispVal]
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readStr t =
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case parse pLisp "f" t of
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Right parsed -> Right parsed
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Left err -> Left $ errorBundlePretty err
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{-# INLINABLE readStr #-}
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sc :: Parser ()
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sc = L.space space1 (L.skipLineComment ";") empty
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{-# INLINABLE sc #-}
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lexeme :: Parser a -> Parser a
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lexeme = L.lexeme sc
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{-# INLINE lexeme #-}
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symbol :: Text -> Parser Text
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symbol = L.symbol sc
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{-# INLINE symbol #-}
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symbol' :: Text -> Parser Text
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symbol' = L.symbol' sc
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{-# INLINE symbol' #-}
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pNil :: Parser LispVal
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pNil = symbol' "nil" >> return Nil
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{-# INLINE pNil #-}
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integer :: Parser Integer
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integer = lexeme L.decimal
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{-# INLINE integer #-}
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lispSymbols :: Parser Char
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lispSymbols = oneOf ("#$%&|*+-/:<=>?@^_~" :: String)
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{-# INLINE lispSymbols #-}
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pLispVal :: Parser LispVal
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pLispVal = choice [pList, pNumber, pSymbol, pNil, pString]
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{-# INLINE pLispVal #-}
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pSymbol :: Parser LispVal
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pSymbol = (Symbol . T.pack <$> lexeme (some (letterChar <|> lispSymbols)))
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{-# INLINABLE pSymbol #-}
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pList :: Parser LispVal
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pList = List <$> between (symbol "(") (symbol ")") (many pLispVal)
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{-# INLINABLE pList #-}
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pLisp :: Parser [LispVal]
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pLisp = some pLispVal
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{-# INLINE pLisp #-}
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pNumber :: Parser LispVal
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pNumber = Number <$> integer
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{-# INLINE pNumber #-}
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pString :: Parser LispVal
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pString = do
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str <- char '\"' *> manyTill L.charLiteral (char '\"')
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return $ String (T.pack str)
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{-# INLINABLE pString #-}
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