There really needs to be a JVM crash-course for clojure... I can understand the syntax well-enough, but I want to know what java libs i need/how i use them/etc. ie. when I have to "leave clojure".
Clojure has been around long enough that people have wrappers around most of the interesting common use java libs. If you're looking for something domain specific then it's usually better to find which java libs cover the domain and work from there.
Here is a talk on it: http://www.infoq.com/presentations/Clojure-Java-Interop
I confess I haven't watched that talk yet and only remembered hearing about it as I wrote this. But I imagine it is a good Launchpad.
Navigating the Java terrain is comical. Often, performing what I would consider a library's basic use-case involves the collaboration of multiple objects I never could've reverse-engineered from the API docs. Yet the library doesn't throw me a bone with any sort of `## Usage` overview.
Fortunately, it seems nobody else knows how to do trivial things with Java (or libraries like Bouncy Castle) either, so I've found it reliable to lean on google queries to find the 1,000 questions that have already been asked and answered.