Python can hot-reload an application from scratch, too. The idea here is to not reload everything from scratch, but to redefine functions incrementally/iteratively as you work.
if i change anything in filters.scm then i (load "filters.scm") instead of just sending a snippet to the interpreter to eval. i have this happen when i save the file. same thing, except i never have to worry about sending code or a mis-match between editor and repl. it also forces you to be more organized with code so that you don't override global state. i just code, save, code, save. you can have hooks run things after every save etc ...