Comment by MarceColl

I implemented something similar for Common Lisp: https://github.com/marcecoll/rekishi

The idea was that you don't have files, just functions that you can bring in and out of scope while editing. You have branches per-function. This all worked more or less transparently to the user using the normal emacs Sly Common Lisp flow.

It was implemented overriding the +DEFUN+ macro, so function re-definitions automatically serialized and created a new entry in the DB.

The Proof-of-Concept used SQLite, but I also envisioned a postgres backed version for jamming on programs with your friends in real time.