On Wed, 28 Jul 1999, Hans Aberg wrote:
> At 14:02 +0100 1999/07/28, D. Tweed wrote:
> >> As for a math description of references, one could take the view that one
> >> always constructs objects a, with references r. Then what is indicated in
> >> the language is often the object pairs (a, r) modulo the equivalence
> >> relation that the references differ.
> >
> >I'm not sure this is a useful view to take given Lennart & Fergus's
> >responses to my previous post saying that the actual references
> >corresponding to named values in a compiled program can fluctuate over the
> >course of program evaluation for various reasons. (I must admit I was
> >surprised that this happens but I guess that's because the FL
> >implementations in textbooks aren't that close to Power-User Haskell
> >Systems(TM) like ghc & hbc :-) )
>
> If this is a problem, one should create a type of reference that is stable
> during the processes. A "reference" need not be something specific, such as
> a computer address, but could be viewed as method that can be used to
> address the object.
I think I misinterpreted what you originally wrote. I'd thought that you
were trying to produce an `explanatory theory' explaining what would be
happening if the original req idea (comparing internal representations)
were to be implemented; I see now that you were describing how you could
implement `language defined references' with semantics which mean that the
problems that were pointed out don't happen. Clearly with the new proposal
assigning references at once & for all at creation time is by construction
an ok model.
___cheers,_dave______________________________________________________
email: [EMAIL PROTECTED] "He'd stay up all night inventing an
www.cs.bris.ac.uk/~tweed/pi.htm alarm clock to ensure he woke early
work tel: (0117) 954-5253 the next morning"-- Terry Pratchett
