This is a relevant answer. Thank you. We're using Integrant already so yes, I can mostly work in a REPL without restarting. But the restarts are more like 15 s

This is a relevant answer. Thank you. We're using Integrant already so yes, I can mostly work in a REPL without restarting. But the restarts are more like 15 seconds. I'll have to measure and see what's so slow. My rdev platform is Cursive on a 16G MBP. And while I'm commenting, yes, we have a reason to run on JVM (a lot of legacy Java code we probably want to interface with later on). So thanks to other commenters for suggesting Node.js and Common Lisp, but not possible. :)