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> I'm not sure what's neutered about Rust's current plans for generators
They're neutered because they can't suspend and transfer control to a function other than the one that called them ("Note also that "coroutines" here are really "semicoroutines" since they can only yield back to their caller." https://lang-team.rust-lang.org/design_notes/general_corouti...) and you can't pass values into resume and get them out from the yield statement in the coroutine (https://github.com/rust-lang/rust/issues/43122#issuecomment-...).
> and they aren't separate from async, they're the foundation that async desugars to.
Yeah I just looked it up again and I don't know why I had it in my head that they were separate, you're correct, they are the same thing under the hood, so honestly that eliminates my biggest problem with them.
> 'm also not sure what your objection is to Polonius, which, so far, is still just a strictly more permissive version of the borrow checker, with nothing new to learn on the user end.
The entire model is different under the hood, though, since it switches from lifetimes+borrows to loans, and so in order to fully understand its behavior the user really would have to change their mental model, and as I said above I'm a huge fan of the lifetimes model and less so of the loan model. I just feel like it's much more natural to treat the ownership of a memory object and therefore amount of time in your code that object lives as the fixed point, and borrows as wrong for outliving what they refer to, then to treat borrows as the fixed point, and objects as wrong for going out of scope and being dropped before the borrow ends, because the fundamental memory management model of Rust is single ownership of objects, moves, and scope based RAII via Drop, so the lifetime of an object kind of is the more basic building block of the memory model, with borrows sort of conceptually orbiting around that and naturally being adjusted to fit that, with the checker being a way to force you to adhere to that. The loan based way of thinking would make more sense for an ARC-based language where references actually are more basic because objects really do only live for as long as there are references to them.
Self-referential structs work fine in Rust and always have.
https://play.rust-lang.org/?version=stable&mode=debug&editio...
The compiler will correctly prevent you from moving the value.
The other way to have a struct that starts out as non-self-referential and then becomes self-referential can be achieved with `unsafe` and `Pin::new_unchecked`, which is how `async {}` is handled.
I may be out of my depth here as I've only casually used Rust, but this seems similar to Swift's proposed lifetime dependencies[1]. They're not in the type system formally so maybe they're closer to poloneius work
[1]: https://github.com/apple/swift-evolution/blob/3055becc53a3c3...