Let's talk about writing code in Python. You write a script and either run it through your IDE or via the command line via Python pythonscript.py. With D, I write some code and feed it through the compiler like dmd scriptname.d.

With Clojure in addition to all the cruft I have to learn (Emacs, leinegen...etc), I still have to know something of Java. One of the big selling points is integration. If I know zero Java, how am I supposed to make use of the various classes? Even if I largely stick to just Clojure, how does one interpret the Java stack traces? What is the best method for running via the JVM? How do I performance tune the JVM? How do I use GUI frameworks that are largely all OO Java?