This is one of the most concise tutorials on how generators, coroutines and futures/promises are related (from first principles) that I've seen.<p>I'm hopeful that eventually promises and async/await fade into history as a fad that turned out to be too unwieldy. I think that lightweight processes with no shared memory, connected by streams (the Erlang/Elixer, Go and Actor model) are the way to go. The advantage to using async/await seems to be to avoid the dynamic stack allocation of coroutines, which can probably be optimized away anyway. So I don't see a strong enough advantage in moving from blocking to nonblocking code. Or to rephrase, I don't see the advantage in moving from deterministic to nondeterministic code. I know that all of the edge cases in a promise chain can be handled, but I have yet to see it done well in deployed code. Which makes me think that it's probably untenable for the mainstream.<p>So I'd vote to add generators to the Rust spec in order to make coroutines possible, before I'd add futures/promises and async/await. But maybe they are all equivalent, so if we have one, we can make all of them, not sure.