On Tue, 14 Oct 1997 08:27:00 -0700,
Kent M Pitman <······@world.std.com> wrote
in comp.lang.lisp:
... most of the text omitted...
>Sounds like
>a good candidate for next time around, though. At least
>TYPE-SPECIFIER-P ...
Yes, I believe it will be nice indeed to include
TYPE-SPECIFIER-P in the language at the next opportunity.
In my opinion, it would be most useful if it tests for
an `actual' type specifier, because this is the version
that users cannot write on their own (or can but at great expense).
In other words, the version where (TYPE-SPECIFER-P FOO) returns
true iff, in the current lexical _and_dynamic_ context,
it is possible to provide a definite answer (be it yes
or no) to a TYPEP/SUBTYPEP question concerning FOO (i.e.,
it is not an error to ask such a question).
The other version, where TYPE-SPECIFIER-P merely tests
for a `potential' type specifier (i.e. if it is a symbol,
or a list built according to the specific syntax rules),
is much easier for the users to implement themselves.
I am *very grateful* to Kent Pitman for his coverage
of the issue.
Best regards,
Vassil.
Vassil Nikolov <········@bgearn.acad.bg> (+359-2) 713-3813
Department of Information Research
Institute of Mathematics and Informatics fax: (+359-2) 9713649
Acad. G. Bonchev, block 8, Sofia 1113, Bulgaria