One thing that I love about Clojure is that the Read-Eval-Print-Loop (REPL) enables me to redefine functions on the fly, without restarting anything. This makes trying things, making changes, and trying them again very fluid. Trying stuff, changing it, and trying it again pretty much sums up how I write code.
|Evaluate the expression before the cursor|
|Evaluate top-level expression at the cursor|
|Run test under cursor|
|Run all tests in namespace|
|Re-run last test action|