Strudel REPL is a browser-based music programming language based on Tidal Cycles which is based on Super Collider.

https://strudel.cc/ Strudel on HN: https://news.ycombinator.com/item?id=45571822

I have not used SuperCollider in a long time, but there used to be a nice Clojure front-end (with some Emacs integration) and it looks like that still exists even if most recent commit was 8 months ago: https://github.com/overtone/overtone

Worth mentioning the "supercollider-vscode" extension - makes Supercollider dev experience much smoother than it was a decade or so ago.