app/Main.hs

   1 module Main where
   2 import Text.ParserCombinators.Parsec hiding (spaces)
   3 import System.Environment
   4
   5 data LispVal = Atom String
   6              | List [LispVal]
   7              | DottedList [LispVal] LispVal
   8              | Number Integer
   9              | String String
  10              | Bool Bool
  11
  12 symbol :: Parser Char
  13 symbol = oneOf "!#$%&|*+-/:<=>?@^_~"
  14
  15 spaces :: Parser ()
  16 spaces = skipMany space
  17
  18 readExpr :: String -> String
  19 readExpr input = case parse (spaces >> symbol) "lisp" input of
  20     Left err -> "No match: " ++ show err
  21     Right val -> "Found value"
  22
  23 main :: IO ()
  24 main = do
  25     args <- getLine
  26     putStrLn (readExpr args)