gitRules/tools/translator.hs

import System.Environment


mapFilter :: (a -> Maybe b) -> [a] -> [b]
mapFilter fn = worker . map fn
    where
        worker (Nothing  : rest) = worker rest
        worker ((Just x) : rest) = x : worker rest
        worker [] = []


translate :: String -> [String] -> [String]
translate language = mapFilter worker
    where
        worker ('|':x:y:'>':line)
            | [x,y] == language = Just line
            | otherwise         = Nothing

        worker line = Just line
            

main :: IO ()
main = do
    args <- getArgs
    case args of
        [language] -> interact (unlines . translate (language) . lines)
        _ -> putStrLn "translator language"