[Haskell-beginners] Improve my FFI code please...

[Edward Z. Yang]

The code looks basically fine.  Good job getting to this point.

* It is probably a good idea to give Ptr Word8 a newtype; something like
  Wiimote, to semantically represent what it is.

* Everyone loves bracketing functions! Write the function

    withWii :: String -> (Ptr Word8 -> IO ()) -> IO ()

  Don't call the inner lambda if getting the Wiimote fails.

* You can probably simplify 'test' a little bit by using exceptions
  and guards.  For example, instead of 'case status' you can write
  'when (not status) $ error "FAIL"'.  But this is a matter of taste
  and what you have isn't nested too deep.

Cheers,
Edward