Here is what he said then re Arc: "My prediction: someone will get tired of waiting, and they'll Torvalds Arc into obsolescence before it's ever released. (If you don't get the reference, it's what Linux did to GNU Hurd)."
But the great thing about Lisps is that they can't get stuck in the past.
For example, if, say, Python didn't have decorators and you wanted to add them in, you'd have to present the idea in a PEP, get approval from Guido, write some code, et cetera. In Common Lisp, you just write some reader macros and that's it[1]. If Python stopped being maintained, it would lag behind other languages, but the fact that the Common Lisp spec hasn't been updated since 1996 doesn't make it any less modern.
A more relevant example: Lisp doesn't have hash table literals, which every "modern" language these days has, but those can also be added, trivially in less than fifty lines[2] of CL code, and suddenly Common Lisp is modern again.
In programming languages, having 3 proper solutions to a problem is worse than having a single proper default solution - simply due to the overhead of first having to choose, and then the unneeded difficulty when reading other people's code who chose a different lib for the same thing.
For things such as hash table literals, you're not supposed to simply have some way of doing it - you're supposed to have a good and commonly used way of how most everyone else would be doing it and representing them in his/her code. Having a bunch of nonobvious, nonstandartized ways alone hurts readability, maintenance and reusability - and thinking that it is okay is a sign of being stuck in the past.
Being able to add it trivially yourself is an order of magnitude worse - because results in everybody rolling out his own. If you want to make an usable ecosystem (not just 'language core') then you have to make sure that for all/most commonly needed things, the default 'batteries included' or 'batteries taken from first google result' work well, not that it's simply possible to get them somehow.
You know, people say that Common Lisp "is the same as it was" but I dunno. Even if the spec is the same a lot of new libraries are coming out that're changing the playing field, like LiL (Lisp interface Library) or STMX (Software Transactional Memory).
I still do think that we need some new Lisps to do new stuff which can then be cherry picked and so on by new Lisps though.
Yes, but its not the features per se that make Clojure and Racket different from CL; any feature in these languages can be tacked on top of CL fairly easily by a half-decent hacker.
What makes these languages different is their vibrant communities. I do hope they get faster implementations out sometime :) (and allow people the freedom they've been used to in the CL world).
