RE: foreignObjToAddr

[Simon Marlow]

> Much of the "overhead" of StablePtrs at the moment is due to 
> the hash table and reference count business that is
> implicitly performed by the stable pointer routines.  So
> far, I haven't seen a good explanation as to why this is
> actually needed.  If we would get rid of it, StablePtrs
> would be much more light weight.

The hash table is there to ensure that if you make two StablePtrs for the
same object, they will compare equal (see our paper on weak pointers etc.).
This might not be necessary in some situations, so I agree we could have a
lightweight version.

Cheers,
        Simon