Issue EXIT-EXTENT, v5

[Kim A. Barrett <IIM@ECLA.USC.EDU>]

MINIMAL: I don't agree with this, for reasons I have already discussed
somewhat.  Basically, I feel this seriously damages the semantics of the
language, playing havoc with both UNWIND-PROTECT and the definition of
dynamic-scope. 

MEDIUM: Even though the intent of this proposal is what I want, I don't believe
it is really ready for voting yet because the current proposal is poorly
written.  I agree with Moon's comment that this may be hard to write in a
reasonably implementation-independent way.  My intuition is based on the
nesting of forms, but I'm not sure how constraining a writup based on that
would be (though obviously somewhat, since the technique Symbolic's uses would
seem to be invalidated by acceptence of something like this proposal).

This is a hard issue.  Some people feel that MINIMAL is essential because
MEDIUM is too expensive/restrictive for implementors, while other people feel
that (a cleaned up) MEDIUM is essential because MINIMAL is too
expensive/restrictive for users.  Since I favor MEDIUM I would hate to see
this issue die with nothing at all being said, since that can be interpreted as
defacto MINIMAL.  I don't know if I'm going to be able to find the time to
write up anything more coherent though.  Part of the problem I've encountered
when I've tried to do so, is that I think this whole issue is sort of
misdirected.  The problem that needs clarification isn't the extent of exits,
its the dynamic environment in which cleanup forms are executed (in spite of
the fact that the proposal says the extent of other dynamic-extent entities
should be the subject of seperate proposal(s), a claim which I totally disagree
with).  UNWIND-PROTECT cleanup forms are the only place where these proposals
make a difference (to the user).

kab
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