ConstituentParser

ConstituentParser.hs

module ConstituentParser
    where

import Text.ParserCombinators.Parsec
import Control.Monad
import Control.Applicative ((<$>))


symbol = oneOf "!#$%&|*+-/:<=>?@^_~"

parseSymbol = Symbol <$> many1 (letter <|> digit <|> symbol)

parseList = List <$> sepBy parseConstituent spaces

parseConstituent =  try (skipMany space >> parseSymbol)
                <|> try (do skipMany space
                            char '('
                            x <- parseList
                            char ')'
                            return x)

data Constituent = Symbol String
                 | List [Constituent]

instance Show Constituent where
    show (Symbol x) = x
    show (List x)   = "(" ++ unwords (map show x) ++ ")"