What you just described is pretty much universally handled by editor integration.... I can't imagine anyone actually develops lisp without this. The editor is

What you just described is pretty much universally handled by editor integration.... I can't imagine anyone actually develops lisp without this. The editor is hooked directly up to a running image.. a keypress (or two) causes an expression to be executed in the running image... you can flip to the REPL and goof around directly and/or at the same time work from one or more editor buffers and selectively execute code as you desire. You can bust into the debugger whenever you feel like it, etc etc. Someone else described it better above I think - but this image-based interaction is one of the most attractive things for many - it goes well beyond just having a REPL where you can evaluate code... lisp was basically designed around the idea of interactive development. If you think this through to a large, complex project - you can have a giant running application, working in production, and still attach to it with an editor/environment and debug it live... that's hard to do with anything else.