2nd generation LOOP macro

[Daniel L. Weinreb <dlw at SCRC-TENEX at MIT-MC>]

    Date: Friday, 27 August 1982  21:11-EDT
    From: Scott E. Fahlman <Fahlman at Cmu-20c>

    Well, it is OK to write a portable package that explicitly requires
    something from the yellow pages, so we could still use your portable
    code and include the LOOP package with it.

The main problem with this is that it introduces a new phenomenon.  "I
thought that I'd use Moon's nifty new code-walker to improve my hairy
language extension, but unfortunately it uses the
Moon/Burke/Bawden/whomever LOOP package and so when I load it into my
environment it smashes my own LOOP package, so I can't use it." This is
a fundamental problem with the whole idea of the yellow pages; I don't
think there is any solution, so we should just live with it in general.

I think that it is important that LOOP go into the white pages, so that
our language has some reasonable way to get the same power in iteration
that other languages have, but obviously we need a real solid proposal
before this can be discussed.  If it is necessary to leave LOOP in the
yellow pages for a while before it is adopted, that is unfortunate but
acceptable.  

However, I'd like it to be made clear that LOOP is being seriously
proposed for eventual inclusion in the white pages even if it is only
going into the yellow pages for now, so that people will be encouraged
to try it, suggest improvements, and use it instead of ignoring it and
writing their own equivalent but gratuitously incompatible LOOP macros.
(Conceptually-different and non-gratuitously incompatible
keyword-oriented iterators are perfectly OK, of course.)