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From: bruce@liverpool.ac.uk
Subject: Re: Scheme requires '() to be a true value (was Re: GNU Extension Lang.)
In-Reply-To: wilson@cs.utexas.edu's message of 24 Oct 1994 22:19:36 -0500
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>>>>> "Paul" == Paul Wilson <wilson@cs.utexas.edu> writes:

> I assume that you're not going to implement a separate function
> namespace for Scheme code.  (Scheme programs freely use first-class
> procedures, and that is much more awkward with separate namespaces;
> it would probably break the large majority of nontrivial Scheme
> programs, and half the trival ones too.)  What is your plan for
> using the extra binding slots?

I think the reasoning behind several of the changes is to make this
new language pretty much a superset of emacs-lisp, so that emacs can
use the same extension language.

Emacs lisp programs really do use the same symbol for values and
functions, and certainly use nil to represent false.

From the comments of several people, it looks as though some of these
decisions are mistakes: the emacs lisp code should be changed.

In particular, it looks as though the conflation of #f and '(), and
keeping the multiple slots in symbols (especially the function slot)
are bad ideas for compatibility with scheme.  I can't see any problem
with dynamic variables and case sensitivity: presumably the first has
been done before, and the second is surely not going to cause
problems?
-- 
Bruce                   Institute of Advanced Scientific Computation
bruce@liverpool.ac.uk   University of Liverpool

