visible hash tables

[Jon L White <edsel!jonl@labrea.stanford.edu>]

I think you've made a useful observation that there a whole slew of potential
(or real) data types in CLtL for which there is no commonly accepted print
syntax, and for which the #S syntax could be naturally extended to cover.
BYTE-SPECIFIER comes to mind, as well as RANDOM-STATE, PATHNAME, HASH-TABLE, 
PACKAGE, READTABLE, STREAM, (compiled) FUNCTION, and non-simple ARRAY and 
ARRAY with specialized element-type not among {'bit', 'string-char', 'T'}.

On the other hand, I may have to argue against this unifying approach in at 
least one or more of the important cases at hand.  Lucid, like Symbolics, 
already uses the #P"..." approach to pathnames, and probably wouldn't like 
to go to a more space-wasting format.  And for "database"-like types such
as packages and streams, using something like #S would be a gross over- 
simplification; recursive descent throught the slots would indubitably
have incestuous circularities.

Incidentally, both you and Touretzky forgot that hash-tables have two
additional interesting properties beyond the :type and :size -- the
:rehash-size and :rehash-threshold.  Hash-tables wouldn't be fully
reconstructable from the printed format unless this information were
also included.


-- JonL --