main :: IO ()
main = do
  args <- getArgs
  case args of
    [x, y] -> atDiffFP x y
    _ -> putStrLn "expected two argument filenames"
main :: IO ()
main = do
  args <- getArgs
  case args of
    [x, y] -> atDiffFP x y
    _ -> putStrLn "expected two argument filenames"
main = do
  args <- getArgs
  case args of
    [x, y] -> atDiffFP x y
    _ -> putStrLn "expected two argument filenames"