Ask HN: Procedural music with Web Audio – any libraries out there?

Howdy all! I'm wondering if anyone knows what the current state of web audio procedural music libraries is? I have a mate who's looking to code up an in-browser generative music page and I'm not sure where to start re- easy to use libraries. I did a ChucK course some time ago and was really excited to see ChuckJS and the Emscripten port of ChucK, but for the life of me I can't get the thing to build and it kind of looks abandoned (latest version on Git won't compile for me; it appears to be in a half-merged state). Would have loved something like that -- (see http://chuckdemos.com). Would be interested to hear what others have come across.