Interesting article, introduced me to a whole bunch of lisps I had no idea existed.<p>Slightly tangentially, can anyone explain to me what the supposed advantage of using Lisp is over languages such as Python and Ruby (which also provide functional programming, dynamic typing, etc)? I certainly feel that I'm more productive in some languages than others, eg, I can do the same things faster in Ruby than in Java. When I tried working in Clojure for a few mini projects, I enjoyed using it, but didn't feel any more productive than in Ruby.<p>I actually like the Lisp-like syntax, but I usually find myself either a) tying myself in knots trying to avoid the use of variables, or b) missing Ruby's object system. It seems like these might be problems that stem from inexperience, can anyone else comment? Is it worth reading "On Lisp" or SICP to learn how to take advantage of Lisp's unique features (macros and so on)?