Hello,
I've been looking over adding weak hashtable support to ECL, when I took a closer look at slime's use of them. Maybe they were used more aggressively in the past, but now they seem to only be used by the presentation contrib. I'm not sure they're necessary for that- as long as they're in the REPL shouldn't the presentation keep an extra reference to them? Perhaps a better way to deal with this is to have slime indicate what objects its holding and/or clear this buffer when it stops using them. This might better belong in a per-connection thing, and I wanted some advise on this before I started hacking on this.
Are the weak hashtables legacy? Are they going to be used in preparation for something? Is this the only part that needs dealing with? Would it be better still to add weak hashtables to ECL anyway.