import Data.Char (isSpace)
import System.Environment (getArgs)

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

main = mainWith myFunction
  where mainWith function = do
          args <- getArgs
          case args of
            [input,output] -> interactWith function input output
            _ -> putStrLn "error: exactly two arguments needed"
        myFunction = firstWords

splitLines [] = []
splitLines cs =
    let (pre, suf) = break isLineTerminator cs
    in  pre : case suf of 
                ('\r':'\n':rest) -> splitLines rest
                ('\r':rest)      -> splitLines rest
                ('\n':rest)      -> splitLines rest
                _                -> []

isLineTerminator c = c == '\r' || c == '\n'

firstWords :: String -> String
firstWords input = unlines (map firstWord (splitLines input))

nonSpace :: Char -> Bool
nonSpace = not . isSpace

firstWord :: String -> String
firstWord ws = takeWhile nonSpace $ dropWhile isSpace ws