Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!SESAME.STANFORD.EDU!mkatz
From: mkatz@SESAME.STANFORD.EDU (Morris Katz)
Newsgroups: comp.lang.scheme
Subject: "unspecified" and SET!
Message-ID: <8906212117.AA20117@sesame.Stanford.EDU>
Date: 21 Jun 89 21:17:54 GMT
References: <10160.890620.ALAN@ML.AI.MIT.EDU>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 19

At the R*RS meeting in Snowbird we discussed the possibility of adding some
form of multiple values to Scheme and allowing continuations to accept multiple
values.  I wonder if the solution to the problem of what should be returned by
side effecting procedures like SET! is to just have them return no values (i.e.
a zero arity multiple value).  As long as continuations can handle multiple
values appropriately, it seems to me that this solution would have many, if not
all, of the advantages of #!UNSPECIFIED without introducing many of the
undesirable side effects.

					Morry Katz
					katz@polya.stanford.edu

P.S.  After the meeting at Snowbird, Guy Steele and I came to an agreement as
      to the correct of the two conflicting semantics for multiple values to
      continuations that we proposed.  At that time, we believed that this
      solution would probably be acceptable to the great majority of the
      community.  Is there interest in having the proposal written up for
      future consideration?  I would be willing to strain my memory in an
      attempt to creat such a proposal if there is genuine interest.