null character cleanup

Clean.hs

-- file: Clean.hs
-- removes null characters

import System.Environment (getArgs)

removeNull :: [Char] -> [Char]
removeNull [] = []
removeNull (x:xs)
    | x == '\000' = [] ++ removeNull xs
    | otherwise = [x] ++ removeNull xs


readWriteFile function inputFile outputFile = do
    input <- readFile inputFile
    writeFile outputFile (function input)

main = mainWith removeNull
    where mainWith function = do
            args <- getArgs
            case args of
                    [input, output] -> readWriteFile removeNull input output
                    _ -> putStrLn "usage hint: ./Clean <input file> <output file>\n"