Patai, I asked a similar question about a week ago, inquiring about efficient buffers for audio. I got a good response:
http://thread.gmane.org/gmane.comp.lang.haskell.cafe/67258/focus=67293 Well, the general lesson seems to be that using stream fusion or something analogous is the way to go. In this particular case I don't need any fancy processing, and I have no feedback loops. All I do in my mixing routine is to calculate a weighted (volume+panning) sum of samples and stretch them in time as dictated by their frequency. The song is flattened into a series of play states first, so all the information required for mixing is readily available.
I could try rewriting the mixer to return an iterative generator function instead, which could be passed to an appropriate sound interface. The latter would have to be written once and for all. Gergely -- http://www.fastmail.fm - Does exactly what it says on the tin