They're so different and yet so similar it's probably best taking them one topic at a time. I've written nontrival things in all of those except clojure, but I think I still have a pretty good idea what it's about from a bit of playing around, reading the notes of others, time spent in PLT Scheme etc. I hope this is helpful for some people looking to dive in--remember, all of this "IMO/IME".Type S