failIfExists :: FilePath -> IO ()
failIfExists file = do
  exists <- doesFileExist file
  when exists $ fail $
    printf "File %s already exists. To force supply --force." file
failIfExists :: FilePath -> IO ()
failIfExists file = do
  exists <- doesFileExist file
  when exists $ fail $
    printf "File %s already exists. To force supply --force." file
failIfExists file = do
  exists <- doesFileExist file
  when exists $ fail $
    printf "File %s already exists. To force supply --force." file