Re: `StablePtr` in `ST`
David Feuer <[email protected]>
| Newsgroups | gmane.comp.lang.haskell.glasgow.user,gmane.comp.lang.haskell.ghc.devel |
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| Message-ID | <CAMgWh9sLaeaS0tb3qEuQf6PPQQgNs-hNb=xYG4VrTYXV4XV8HA@mail.gmail.com> |
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 <[email protected]> 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 <[email protected]> > 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 >> [email protected] >> http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users >> > _______________________________________________ Glasgow-haskell-users mailing list [email protected] http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users