Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!ut-emx!linus!GLOWWORM.LispM.SLCS.SLB.COM!7thSon
From: 7thSon@SLCS.SLB.COM (Chris Garrigues)
Newsgroups: comp.lang.lisp
Subject: Something pathological
Message-ID: <19900117221851.0.7THSON@GLOWWORM.LispM.SLCS.SLB.COM>
Date: 17 Jan 90 22:18:00 GMT
Sender: news@linus.SLCS.SLB.COM
Distribution: usa
Organization: Schlumberger Laboratory for Computer Science
Lines: 20

I frequently use setf of backquoted forms to do destructuring:

	(setf `(,x ,y) (function-which-returns-a-two-element-list bar))

(I realize that this isn't actually part of legal common lisp, but it is
useful.) The other day while thinking about this ability, I came up with
an odd piece of code.

Should this actually expand into something reasonable:

	(setf `(,(second x) ,(first x)) x)

It looks to me like it should swap the first and second elements of the
list x.  It doesn't work on my LispM, however, because the two
operations aren't done in "parallel".

I lost sleep over this silliness last night.


Chris