[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: A (possibly interesting) macro
- To: BAK at MIT-AI
- Subject: Re: A (possibly interesting) macro
- From: George J. Carrette <GJC at MIT-MC>
- Date: Sat ,11 Oct 80 18:10:00 EDT
- Cc: LISP-FORUM at MIT-AI
Date: 11 OCT 1980 1626-EDT
From: BAK at MIT-AI (William A. Kornfeld)
A definition of SEQ is:
(defmacro seq (&rest forms &aux replacement)
(cons (car form) (subst replacement '* (cdr form)))))
 SUBST doesn't know anything about the semantics of lisp.
So you should say (meta-eval form '(*) (list replacement)).
[One such meta-evaluator is MC:LIBMAX;META >]
 (SEQ (FOO) (BAR * *)) causes multiple evaluation of (FOO).
Its not really clear that thats what is intended, because
SEQ looks like it might be implemented as
(defmacro SEQ (&REST FORMS)
`(prog (*) ,@(mapcar #'(lambda (u) `(setq * ,u)) forms)
Which I think is much more natural for the type of programming
I think "*" in SEQ should act just like a variable, especially since
it looks so much like the "*" in the read-eval-print-loop.