Tue, 5 Aug 2003 17:02:08 +0100
On Tuesday 05 August 2003 4:00 pm, Simon Peyton-Jones wrote:
> | > id# :: (a :: # ) -> a
> | > id# x = x
> That should really be rejected. You couldn't call it because you'd have
> to instantiate 'a' to Int# or Double#, and that would mean different
> code for different calls.
GHC (after modifying the parser to allow # to stand for the kind of unlifted
type) seems to behave very nicely with this definition - it does not generate
any code for it, and inlines its uses; so the problem never actually arises
(but I expect it would for more complex code). I guess I shouldn't rely on
> One clue: take a look at the UArray library.
> UArray is parameterised by Int, Float, Double, but it describes arrays
> that hold Int#, Float#, Double# respectively. Maybe you could re-use
> ideas from there?
Interesting! It seems that just writing wrappers around my new primitive
operations, that do boxing and unboxing as appropriate, works out just fine -
GHC does all the expected unboxing. So it is not worth trying to work with
boxed values directly. Great, thanks! :-)