Re: `StablePtr` in `ST`

You also need to avoid inspecting the StablePtr itself, which is just a number, to maintain purity. The whole thing is a bit weird. Why do you want this anyway? On Wed, Aug 21, 2019, 7:39 AM David Feuer wrote:

So something like

newtype StablePtr a = StablePtr (StablePtrST RealWorld a)?

I suppose that could work with some discipline. You have to assume that foreign code doesn't pick its address out of a hat and so something silly, but I guess you pretty much have to assume that anyway.

On Wed, Aug 21, 2019, 5:00 AM Matthew Farkas-Dyck wrote:

...

I have been doing some work where i want `StablePtr`, but also to not be confined to `IO`. I saw the following comment in "compiler/prelude/PrimOp.hs":

Question: Why @RealWorld@ - won't any instance of @_ST@ do the job? [ADR]

It has been there for 20 years. What is the answer? If it is safe i'll send the patch generalizing these operations. _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users