A Parser

README.mdown

This sucks right now, so don't use it as an example for anything. I'm just trying to figure this stuff out.

HackTalk.hs

-- This is a really terrible parser I'm working on to learn Haskell & Parsec.
-- Sorry if it makes your eyes bleed.

module Main where

import Control.Monad(liftM)
import Text.ParserCombinators.Parsec
import Text.ParserCombinators.Parsec.Expr
import qualified Text.ParserCombinators.Parsec.Token as P
import Text.ParserCombinators.Parsec.Language

lexer :: P.TokenParser st
lexer  = P.makeTokenParser emptyDef

symbol = P.symbol lexer
parens = P.parens lexer
dot = P.dot lexer
colon = P.colon lexer


data Expr = Var String
          | Selector String
          | Message (Expr) (Expr) (Expr)

instance Show Expr where
    show (Var s) = s
    show (Selector x) = "@selector(" ++ x ++ ")"
    show (Message x y z) = "objc_msgSend(" ++ (show x) ++ "," ++ (show y) ++ "," ++ (show z) ++ ");"


sentence :: Parser String
sentence = many1 $ noneOf "."

sentences :: Parser [String]
sentences = sentence `sepEndBy` dot

word :: Parser String
word = many1 (letter <|> digit)

message :: Parser Expr
message = 
  word >>= \r -> space >>
  word >>= \s -> colon >>
  word >>= \a ->
  return $ Message (Var r) (Selector s) (Var a)


readParser :: Parser a -> (a -> String) -> String -> String
readParser parser trans input =
  case parse parser "HackTalk" input of
    Left err -> "No match: " ++ show err
    Right val -> trans val

readSentences :: String -> String
readSentences = readParser sentences $ unlines . map readMessage

readMessage :: String -> String
readMessage = readParser message (id . show)


main =
  putStr $ readSentences "dawg bark: loudly. cat meow: likeAKitten. haters gonna: hate."