I'm the author of Cursive, a Clojure IDE based on IntelliJ. Cursive currently has a fairly minimal and occasionally frustrating debugger that I'm planning to improve soon. That said, I use it all the time and it works pretty well. It's really nice to be able to debug a REPL session. Currently breakpoints and stepping work well, and expression evaluation somewhat works but is pretty quirky. Types and names are all currently displayed as Java, unfortunately. I'm planning to have a debug REPL per stack frame when I get around to upgrading this part. I'm hoping to get to this sometime within the next month.