>>>>> "David" == David Rush <xxxxxx@bellsouth.net> writes:

David> Yes. And I must admit that in these terms I find this proposal
David> somewhat seductive. However, Per's analogy with the C `&' operator
David> makes very clear how big this issue is. SRFI-17 is tinkering with
David> fundamental language semantics. How does adding *explicit* pointer
David> types and the accompanying pointer-aliasing problems interact with the
David> compiled Schemes? Or how they interact with the garbage collector?

David> Now, I am not totally opposed to this idea, but I rather like
David> the way that things currently work in Scheme. The proposed model of
David> L-values actually seems remarkably close to SML's ref type (which I
David> like), but with an important difference: In Scheme (AFAIU) *all* names
David> are bound to values of ref type, whereas in SML only those names which
David> are explicitly declared to be so are. Scheme includes some magic so
David> that all values of ref type are automatically dereferenced, *except*
David> in the case of SET!. SET-CAR! & friends don't even enter into the
David> picture, they are simply operations on opaque types following the
David> usual Scheme rules.

You might want to check out:

Michael Sperber, Peter Thiemann:
ML and the Address Operator
Proceedings of the 1998 ACM SIGPLAN Workshop on ML
Pages 4--13

The paper addresses pretty much all of these issues.  I'll send
PostScript to anyone who's interested.

--
Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla