Condition Systems in an Exceptional Language by Chris Houser
I recently watched Chris Houser's talk from Clojure/conj 2015 on condition systems in Clojure. I enjoyed the subject, so I decided to write up the talk as a way of encouraging me to really understand it, and in the hope that it might help others understand it.
The last time I heard about Common Lisp's condition system was at a talk by Didier Verna at ACCU in Bristol in 2013 (slides here). It sounded really interesting, but I didn't understand it well enough.
Chris Houser talks about different ways of handling errors in Clojure. Based on examples from Peter Seibel's book, Practical Common Lisp, he describes condition systems, which are also known as resumable exceptions, or restarts.