This is the first time I've seen something like this, but it's greatly broadened my knowledge of Clojure over the past few hours. I've always had trouble trying to find out where to begin. Lisps are foreign to me, and functional programming was and is still a mostly foreign concept. However, things like this that are so simple and understandable make such great introductions.

Kudos to the authors, and you have a thumbs up from me.