Interesting, thanks; though I don't think that what you describe is comparable to L-systems. Just had a look into the book "Unplayed Melodies, Javanese Gamelan and the Genesis of Music Theory" by Perlman, which I have at hand, and didn't find any indications of generative grammars or rewriting; it's rather a set of established patterns ("balungan"); this also corresponds to what my friend has learned about the traditional music in Bali (here is a recording we did together; he plays the traditional slonding instruments): http://rochus-keller.ch/?p=251. The problem with the application of fractal algorithms to music is, that music is actually not "self-similar" in the fractal sense, but there are just repetitions or variations. Music in general is not based on an ever-evolving stream of "fractal noise".

I agree that Gamelan is very beautiful music. Important western composers such as Steve Reich were there and studied the music to adopt the concepts in their compositions (see e.g. https://www.youtube.com/watch?v=TN_YSS06ZcQ&pp=ygUabXVzaWMgZ...). Here a part of the performance where you can see that Reich even adopded the orchestral layout similar to a gamelan ensemble: https://youtu.be/71A_sm71_BI?t=806.

Ok yes I see your point. I think I am guilty of some imprecision here.. More of a family resemblance I guess.