module Main where
import Control.Monad
import Text.ParserCombinators.Parsec hiding (spaces)
import System.Environment

data LispVal = Atom String
             | List [LispVal]
             | DottedList [LispVal] LispVal
             | Number Integer
             | String String
             | Bool Bool

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

spaces :: Parser ()
spaces = skipMany space

parseString :: Parser LispVal
parseString = do
    char '"'
    x <- many (noneOf "\"")
    char '"'
    return $ String x

parseAtom :: Parser LispVal
parseAtom = do
    a <- letter <|> symbol
    b <- many (letter <|> digit <|> symbol)
    let atom = a:b
    return $ case atom of
                "#t" -> Bool True
                "#f" -> Bool False
                _    -> Atom atom

parseNumber :: Parser LispVal
parseNumber = liftM (Number . read) $ many1 digit

readExpr :: String -> String
readExpr input = case parse (spaces >> symbol) "lisp" input of
    Left err -> "No match: " ++ show err
    Right val -> "Found value"

main :: IO ()
main = do
    args <- getLine
    putStrLn (readExpr args)