I've been sitting on an essay in response to some comments about
extensible languages made by Barbara Liskov in her OOPSLA 2009
keynote. I'm happy to announce that the time has come to share my
thoughts. I'd encourage anyone interested in language design to chase
the link to the video footage, which was posted relatively recently
(http://www.infoq.com/presentations/liskov-power-of-abstraction).
Please let me know if you have any comments or questions!
Thanks!
-Jon