I won't die if (SYMBOLP (NOT 'FOO)) => T, but really now...

[George J. Carrette <GJC at MIT-MC>]

I have to admit that "divergences in Common-Lisp from common practice
in the major dialects in use today" doesn't concern me too much.
Aren't there great differences amoung the lisps in fundamental areas,
such as function calling? [E.G. The Interlisp feature such that user-defined
functions do not take well-defined numbers of arguments.]

The kind of thing that concerns me is the sapping away of productivity
caused by continous changes in a given language, and having to
continuously deal with multiple changing languages when supporting
large programming systems in those lisp dialects. I know that given a
reasonable lisp language I can write the macrology that will make it
look pretty much the way I want it to look, and stability in the
language aids in this, because then I wouldn't have to spend a lot of
effort continuously maintaining the macrolibraries.

The aesthetic considerations are then very important. For example, the more
operator overloading which is built-in to a language, and the
more things in a language which have no logical reason to be in
it other than "history," the greater the difficulty of doing the
customization of the language. Considerations of sparseness, uniformity,
and orthogonality are aesthetics, and are known to be important in
language design.

Also, what *is* the source of confusion for a person who has
programmed in lisp for ten years? Have you seen the change in
programming style which happened in MIT Lisps in the last three or four
years, let alone ten? Have you observed the difference between the
lisp appearing in Patrick Winston's book, verses what is
COMMON-PRACTICE in the LispMachine world? Have you seen what Gerry
Sussman has been teaching to six-hundred MIT undergraduates a year?
How could one possibly be worried then about "operator retraining
considerations" over such a trivial item as the empty list not being a
symbol? My gosh, haven't you heard that COMMON-LISP is going for
lexical-scoping in a big way? What about "operator retraining" for that?

-gjc