No, not "every language" has a REPL. Most languages I have worked with don't. It's true that python doesn't have hot-reloading, and that its built-in REPL is

No, not "every language" has a REPL. Most languages I have worked with don't. It's true that python doesn't have hot-reloading, and that its built-in REPL is less powerful than Emacs. But not every lisp has all of that power, either. And personally, I find the Jupyter notebook to offer all that I'd ever want from Emacs, with a better interface. But REPL stands for "read, eval, print loop." My kitchen knife doesn't fail to be a knife because it's missing the corkscrew, flashlight and screwdrivers of a Swiss army knife.