Re: Packages

[Jeff Dalton <jeff%aiva.edinburgh.ac.uk@Cs.Ucl.AC.UK>]

I believe Sean's suggestion is in intention equivalent to the proposal that
packages be replaced by something like Scheme's environments (T's locales).
That is, there would be only one symbol X, but it would have different
values in different environments.  This is the sort of thing that happens
already, e.g. with closures.  The difference is that these environments
would be separate data objects from which you can import values (rather
than their names), etc.

Several people have already expressed the opinion that the environment
approach is insufficiently developed to serve as a replacement for
packages.  That may be so.  In any case, packages and environemnts are more
or less independent since reference with respect to packages is resolved at
read time and with respect to environments at some eval-like time.  So it
should be possible to experiment with environment-like approaches in
Common Lisp.

If anyone from the Scheme would like to explain how environments can be
implemented efficiently I'd be interested, but perhaps this list isn't the
best place to discuss it?

-- Jeff