The dogma killed ASET

[Daniel L. Weinreb <DLW%SCRC-TENEX%MIT-MC@SU-DSN>]

One thing's for sure: this is a nifty demo of the power of the new
5-values SETF scheme.  My taste-buds are oscillating between calling
this a kludge and calling it elegant; when two things can be put
together in an unexpected way to produce a result that's unexpected but
useful, it can be hard to say whether that constitutes a demonstration
of inherent elegance or a programming trick.  Certainly I don't think
that there's anything better for (setf (apply #'aref ...) ...) to expand
into.  If nobody comes up with any real problem with this, I'd say it
constitutes a solution to the problem.  It's probably worth documenting
explicitly somewhere since a lot of people would never guess that this
might work.