Hash table functions

[Andy Freeman <CSD.FREEMAN at SU-SCORE>]

The only way to find the number of entries in a hash table is
to count the number of times that the function arg to maphash is
called.  Since the system has to know this number anyway, even if
as a computation of the number of entries until rehash, the current
size and the threshold, the maphash hack isn't desirable. (If hash
tables are going to be used for large link tables in a discrimination
net, you have to be able to determine the number of entries while
deleting links.)

It is impossible to determine the current size of a hash table.

The user has very little control over a hash table that has been created.
There is no way to shrink it or change its :rehash-threshold/size.
Is this intentional?  (Many applications use tables in distinct
phases, modification and access, and should be able to take advantage
of this.)

-andy
-------