Int vs Word performance?

[Simon Marlow]

Claus Reinke wrote:
> PS. perhaps on newer 64 bit machines, explicitly selecting
>    32 bits can offer savings? I'd certainly expect selecting
>    64 bits on a 32 bit machine to lead to slowdowns.

Unlikely, I'd have thought.  We implement all the explicitly sized integral 
types by zero-extending or sign-extending to the size of an Int/Word. 
That's why there are no primitive types or operations for Word8#, Word16#, etc.

Cheers,
	Simon