On Sun, Jun 08, 2003 at 09:06:07PM +1000, Manuel M T Chakravarty wrote: > Ross Paterson <[EMAIL PROTECTED]> wrote, > > On Wed, Jun 04, 2003 at 11:09:43PM +1000, Manuel M T Chakravarty wrote: > > > StablePtr are used to export references to Haskell values to > > > C, where they are treated as abstract data. In C one > > > traditionally uses (void *) for that purpose (see "man > > > qsort(3)"). We want to make sure HsStablePtr is not to wide > > > to be passed as an argument to C functions expecting such > > > abstract types (such as qsort(3)). > > > > How does HsStablePtr differ from HsDouble in this respect? > > (except that the C side can do even less with > > HsStablePtr.) > > HsDouble is guaranteed to be one of C's floating types; > hence, all operations on floating types can be applied on > values of type HsDouble.
I meant to say that you can't pass an HsDouble to a "polymorphic" C function expecting (void *), so why should you be able to pass an HsStablePtr? Maybe you're arguing that otherwise it couldn't be passed to any legacy C function, whereas doubles can, though to different ones. > > You know it somehow corresponds to a pointer on the Haskell side, > > but that doesn't seem relevant. > > There is no guarantee whatsoever that HsStablePtr is a > pointer on the Haskell side. In GHC, stable pointers are > integral indexes into a table of stable values. Same in Hugs (though that's not a coincidence), which makes it all the stranger that they're treated as pointers. _______________________________________________ FFI mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/ffi
