Interesting. I've followed Matthias' project as I've tried learning the Play framework as well as front end development, and it has been incredibly useful. Incidentally, I learned Scala after I knew Clojure reasonably well, and I feel like I could apply the same arguments in the reverse direction.<p>When it comes to the back end, I'll likely choose Scala 100% of the time. I really believe there is no substitute for a strongly typed ML-derivative for that type of environment. Additionally, there are a strong set of robust scala libraries (Typesafe mostly) that are completely production ready, and java interop is much more natural when you need it.<p>For the front end, I'm currently using Javascript, but I have toyed with the idea of both Scala.js and Clojurescript. This is where Clojure really makes me mad. I feel as though the dynamically typed Clojurescript should be a better fit as a compile-to-javascript language, but in every instance I've tried, Scala.js just works better. It compiles correctly, error messages make sense, much better documented, and there are fewer deviations from the core language. And the clojurescript libraries are mostly terrible in this regard...even the super-hyped ones like Om. My biggest pet peeve are the tutorials that force you to learn unrelated things (like Datomic, Emacs, Ring, etc) to be able to walk through them. I really feel like Clojurescript had a chance to shine here, but I find it far less inspiring than the relatively immature Scala.js. Oh well.