> What I ended up using heavily was REPL to file integration, which gave me the ability to write a function normally, evaluate it in the attached REPL session, and then play around with it in the REPL
When I do REPL driven development in Clojure, that's exactly what I do and that's what other folks that I know mean by REPL driven development (in Clojure): define types, functions and variables in a source file, often in a (comment) form, eval them one by one, and copy the code out of the (comment) form when it's stable enough. I wouldn't type code directly into the REPL; that's not a pleasant experience in Clojure - but might be pleasant in Common Lisp or Smalltalk for all I know. The process that I and others use in Clojure most definitely differs from the process that the OP describes and I lack enough familiarity with Common Lisp to know if the process is more pleasant in that language. I assume it is and I must make time to learn Common Lisp properly some day.
You don't even need the "REPL" buffer to do REPL style development. You can just use the "eval" keybinds of your editor to eval the source code in the files.
For any test/scratch code, just create a scratch file outside your project and write the experiments there, eval'ing as you type. That file could even be an "official" unit test you include in the project.
When I do REPL driven development in Clojure, that's exactly what I do and that's what other folks that I know mean by REPL driven development (in Clojure): define types, functions and variables in a source file, often in a (comment) form, eval them one by one, and copy the code out of the (comment) form when it's stable enough. I wouldn't type code directly into the REPL; that's not a pleasant experience in Clojure - but might be pleasant in Common Lisp or Smalltalk for all I know. The process that I and others use in Clojure most definitely differs from the process that the OP describes and I lack enough familiarity with Common Lisp to know if the process is more pleasant in that language. I assume it is and I must make time to learn Common Lisp properly some day.