nostr:npub1rcr4hpyv9k4f0jnns7kxa5yds8zsxxdcqjd7flcxstu9rw9cv7tsfcnk4e It's guile-nrepl + rail.el:

https://git.sr.ht/~abcdw/guile-nrepl (this repo is ~10 commits behind my local checkout atm)

https://github.com/Sasanidas/Rail