added cabal build system

app/Parser.hs

@@ -0,0 +1,65 @@
+module Parser where
+
+import Monpar
+import Control.Applicative ((<|>), Alternative, many, some)
+import Data.Char (isDigit, digitToInt)
+import Control.Monad (MonadPlus(mzero), void) 
+
+type ZorthAST = [ZorthExpr]
+
+data ZorthExpr = ZorthASTInteger Int
+               | ZorthASTWord String
+               | ZorthASTWordDecl (String,ZorthAST)
+               deriving Show
+
+word1 :: Parser String
+word1 = do
+    x <- sat (\x -> x /= '\n' && x /= ' ')
+    xs <- word
+    return $ x:xs
+
+nonsenseSymbol :: Parser Char 
+nonsenseSymbol = char ' ' <|> char '\n'
+
+skipNonsenseSymbols :: Parser [Char] 
+skipNonsenseSymbols = many nonsenseSymbol 
+
+digit :: Parser Int
+digit = digitToInt <$> sat isDigit 
+
+pZorthUnsignedInteger :: Parser ZorthExpr
+pZorthUnsignedInteger = ZorthASTInteger .  foldr (\n t -> n + t*10) 0 . reverse <$> some digit
+
+pZorthSignedInteger :: Parser ZorthExpr
+pZorthSignedInteger = do
+    char '-'
+    (ZorthASTInteger i) <- pZorthUnsignedInteger
+    return $ ZorthASTInteger $ negate i
+
+pZorthInteger :: Parser ZorthExpr
+pZorthInteger = do
+    skipNonsenseSymbols
+    i <- pZorthSignedInteger <|> pZorthUnsignedInteger 
+    eof <|> void nonsenseSymbol
+    return i
+
+pZorthWord :: Parser ZorthExpr
+pZorthWord = do
+    skipNonsenseSymbols
+    ZorthASTWord <$> word1
+
+pZorthWordDecl :: Parser ZorthExpr
+pZorthWordDecl = do
+    ZorthASTWord ":" <- pZorthWord
+    ZorthASTWord name <- pZorthWord
+    xs <- manyTill pZorthExpr (do { ZorthASTWord ";" <- pZorthWord; return () })
+    return $ ZorthASTWordDecl (name,xs)
+
+pZorthExpr :: Parser ZorthExpr
+pZorthExpr = pZorthWordDecl <++ pZorthInteger <++ pZorthWord
+
+pZorth :: Parser ZorthAST 
+pZorth = some pZorthExpr 
+
+parseZorth :: String -> ZorthAST
+parseZorth = fst . head . runParser pZorth