This post is shameless self-promotion, but I made Dittytoy public and thought it could interest Sonic PI users. Dittytoy is a website where you can make music by code. The (javascript) syntax is loosely based on that of Sonic PI.
Here is an example of a simple ditty: Feedback FM | Dittytoy
You can find documentation here: DittyToy API reference | Dittytoy
Have fun!
Note that you also have to code all synths and filters yourself. Here a vocoder singing the aria “Nessun Dorma” from Puccini’s opera “Turandot”: Vocoder Puccini | Dittytoy
I like the mixer with the sliders ! …
Been enjoying it, following a couple of people. Have yet to try my hand at it, forking or coding things myself. It does sound like it could lead to interesting learning experiences.
While the connection to SPi may be difficult to grasp, it does make me wish we had SPi in the browser. Especially on iPadOS/iOS.
Then, the next step from that would be AUv3. 
At any rate… It’s a fun “toy” which remains in my list of things I’d like to try. Maybe if there were an “Hour of Code” experience to guide me through it…