Correct! I played around with this in the past. It helps less than you'd think. As soon as you have a generic resume parameter, you can no longer drive the generator with a generic runtime.

If I am now writing my own runtime / eventloop to advance my state machine anyway, what exactly am I getting from doing that through an abstraction like the Generator trait?

On top of that, the resume and yield abstraction can get convoluted because a lot of times, you only want to do one or the other, meaning either case needs to support a no-op because a single `yield` always does both.

Lastly, with all input going through a single type, your state machine then needs to handle every possible input at every yield point. That is a lot of `match` statements and branching.

I am sure there are better ways to do this and having generators to express custom iterators would be amazing. But for generic state machines, I don't see much of a benefit.

Nit: the relevant feature is now called `Coroutine`, not `Generator`