Lisp reader and #1=... abbreviations

Hi,

I'm having trouble reading in files which use a lot of
structure-sharing abbreviations.  For example, here is a typical file
(490 KB) which has 18,000+ abbreviations.  Unfortunately, reading this
(with "read") takes about 13 minutes in CMUCL 19d on my test machine.

http://www.cs.utexas.edu/users/jared/Milawa/Sources/ACL2/bootstrap/utilities/proofs/thm-equal-of-booleans-rewrite.proof

We had similar trouble with OpenMCL, and discovered that the reader
was using an association list to manage the abbreviations.  By
replacing this with a hash table, Gary Byers reports speeding up the
process from about 13 minutes to 1.2 seconds.

I wonder if it would be possible to speed this up on CMUCL also?

Thanks!

   Jared

-- 
Jared C. Davis <[email protected]>
3600 Greystone Drive #604
Austin, TX 78731
http://www.cs.utexas.edu/users/jared/