SETF of APPLY

["Scott E. Fahlman" <Fahlman@CMU-CS-C.ARPA>]

I like Guy's new formulation for the SETF of APPLY stuff.

One other thing that should be said is that SETF of APPLY of AREF is
required to work, regardless of how the AREF-setting function is
implemented internally.  The main object of this stuff is to get this
one case to work, and yet an implementation is technically permitted to
implement the AREF setter in some way that does not fit into the
framework described.

-- Scott