Re: GSoC: Emacs Lisp support for GNU Guile

[Richard M Stallman]

     - Remove handling of NIL in Scheme. This special casing is, in my
       opinion, distressingly unclean. This would require adding a new
       ELISP-IF form that accepts #f/nil as false values

We carefully designed ways to handle nil, #f and () in Guile
so as to be able to intermix Lisp and Scheme programs.
That was 14 years ago, and I don't recall what we decided.  But I think
the idea was that #f and () would be eq when viewed
from Lisp, but not eq when viewed from Scheme.

I don't know whether this design was actually implemented.

We should not make changes in this based on a rigid idea that
something is "unclean".  To make the two languages interoperate
properly on the same data requires careful design, and it's
possible that something less than totally elegant is the only
way to make it work at all.