Deprecation, cleanup goals, performance

[Kent M Pitman <KMP@STONY-BROOK.SCRC.Symbolics.COM>]

I agree with Masinter's comments about separating the goal and the
mechanism.

When it does come to talking about mechanisms, though, it's wise to
keep in mind that unlike probably all other languages which provide these
deprecated features, Lisp has meta-level primitives capable of "noticing"
the changes in a way that affects programs. By this I mean that since names
in the language are first class structures (ie, symbols), deprecation comes
at no small cost. I don't think it's wise for us to think of phasing out a
symbol on the Lisp package partly because removing it will lead to all
kinds of confusion with packages using other packages that may or may not
have the symbol (depending on the implementation), problems with print/read
of symbols across systems, etc.