hash table types

[George J. Carrette <GJC@MIT-MC>]

We figured that fixing the root of the problem, the lack of canonicalization
in the hardware database would possibly cost enough time to break a production
development window and put off the introduction of a new hardware item
for a few months, with possible losses in sales of a million dollars
or more for the year. Given this sort of lossage mode one cant stress
enough the importance of having *some* way of getting compatibility
between RELEASE N and RELEASE N+1. Remember that at some time
in "zetalisp" EQUAL on type STRING meant STRING-EQUAL, which was for
better or worse case insensitive. LMI release 2 and presumably also
Symbolics release 6 does away with this. If there is nothing available
which behaves in exactly the same way as the *old* EQUAL-HASH-TABLE
then people can be screwed badly. Remember also that many ugly things
that were left in Common-Lisp from maclisp days (such as the empty
list being a SYMBOL, making the set of all lists and all symbols
have a non-null intersection) were justified soley on the basis that
there was no *automatic* way for people to detect if they were depending
on such lossage and convert their programs. To quote Dave Moon:
"Our customers just wont stand for it." 

-gjc