Late to the conversation, but... I think unit vs integration testing is a good model for comparison. When I'm working in a REPL, I'm trying out individual funct

Late to the conversation, but... I think unit vs integration testing is a good model for comparison. When I'm working in a REPL, I'm trying out individual functions to ensure that they provide the desired results (unit). Most functions are referentially transparent (if not totally pure), so this allows for fast/easy experimentation. If I want to test major code paths in a program, I can call "driver functions" or primary code paths to explore the results (integration). None of this is a substitute for real unit/integration testing, but it makes for some very rapid development. I worked in a lot of "REPL" (Python included) before I had the creme de la creme experience of using Clojure with Spacemacs and Cider. It's truly a different beast, and I'd withhold judgement until you've tried it (or something very comparable).