I would love generators too but I think the more features they add the more interactions with existing features they have to deal with, so it's not surprising that its slowing down.

Generators in particular has been blocked on the AsyncIterator trait. There are also open questions around consuming those (`for await i in stream`, or just keep to `while let Some(i) in stream.next().await`? What about parallel iteration? What about pinning obligations? Do that as part of desugaring or making it explicit?). It is a shame because it is almost orthogonal, but any given decision might not be compatible with different approaches for generators. The good news is that some people are working on it again.