The Revenge of Finalizers

[Simon Marlow]

> I'd hoped that blockFinalizers would be useful for defining other
> primitives but since it won't even work for GHC, I agree that PVar
> will meet most of our needs.  (An even simpler design might be to
> extend our IORef implementations with 'atomicallyModifyIORef'.)
> 
> So, is this a design that we could agree on?  

I like it.  I'd vote for 'atomicModifyIORef' rather than a new PVar
type, though.

Cheers,
	Simon