Parsec example.hs

parseComment :: Parser LispVal
parseComment = do skipMany space
                  char ';'
                  skipMany $ noneOf "\n\r"
                  return $ Null False


parseAtom :: Parser LispVal
parseAtom = do first <- letter <|> symbol
               rest <- many (letter <|> digit <|> symbol)
               let atom = [first] ++ rest
               return $ case atom of
                          "#t" -> Bool True
                          "#f" -> Bool False
                          otherwise -> Atom atom