I think you could do something manageable with yield alone (at least with python-style generators). I've been meaning to try something like this with tornado.

I think you could do something manageable with yield alone (at least with python-style generators). I've been meaning to try something like this with tornado. The general idea is that yielding would either immediately produce a callback or asynchronously "wait" for a previously-generated callback to be run. It would look something like this: doOneThing(yield Callback("key1")) andAnother(yield Callback("key2")) res1 = yield Wait("key1") res2 = yield Wait("key2")