X-Git-Url: https://git.rmz.io/my-scheme.git/blobdiff_plain/d06e8ae01efc00ea0eb6f0bed346032b004aca57..5988ad89d4dd34b63abf5512ce3308ed86ff279d:/app/Main.hs diff --git a/app/Main.hs b/app/Main.hs index 7c987ce..01fd038 100644 --- a/app/Main.hs +++ b/app/Main.hs @@ -1,4 +1,5 @@ module Main where +import Control.Monad import Text.ParserCombinators.Parsec hiding (spaces) import System.Environment @@ -8,6 +9,7 @@ data LispVal = Atom String | Number Integer | String String | Bool Bool + deriving Show symbol :: Parser Char symbol = oneOf "!#$%&|*+-/:<=>?@^_~" @@ -26,12 +28,26 @@ parseAtom :: Parser LispVal parseAtom = do a <- letter <|> symbol b <- many (letter <|> digit <|> symbol) - return $ Atom (a:b) + let atom = a:b + return $ case atom of + "#t" -> Bool True + "#f" -> Bool False + _ -> Atom atom + +parseNumber :: Parser LispVal +parseNumber = do ds <- many1 digit + let a = read ds + return $ Number a + +parseExpr :: Parser LispVal +parseExpr = parseString + <|> parseAtom + <|> parseNumber readExpr :: String -> String -readExpr input = case parse (spaces >> symbol) "lisp" input of +readExpr input = case parse parseExpr "lisp" input of Left err -> "No match: " ++ show err - Right val -> "Found value" + Right val -> "Found value: " ++ show val main :: IO () main = do