Any Lisp is good at editing live process, you just need to give it a REPL. Because of homoiconic nature of Lisp, every step in Read-Eval-Print-Loop differs. Lispers sometimes refer to Lisp REPL as the "true REPL", because non-homoiconic REPLs are rather "interactive shells" in comparison.
Clojurescripters for example can use nbb with the connected REPL and build web-scrapers while interactively "clicking" on buttons and exploring DOM directly from the editor.
In case of Emacs, it is not [just] an editor, technically it is a Lisp REPL loop with a built-in text editor. That's why you can virtually change any aspect of it on the fly, without ever having to restart it.
What's crazy that this allows to have pretty much anything "programmable". Even keyboard macros in Emacs are just series of Lisp instructions. You can compose a macro and then look at its underlying code, modify it and execute it.
Clojurescripters for example can use nbb with the connected REPL and build web-scrapers while interactively "clicking" on buttons and exploring DOM directly from the editor.
In case of Emacs, it is not [just] an editor, technically it is a Lisp REPL loop with a built-in text editor. That's why you can virtually change any aspect of it on the fly, without ever having to restart it.
What's crazy that this allows to have pretty much anything "programmable". Even keyboard macros in Emacs are just series of Lisp instructions. You can compose a macro and then look at its underlying code, modify it and execute it.