> it was my impression that there is no firm commitment to stabilizing GAT
Certainly, but not in the sense of being uncertain about whether or not GAT are worthwhile, only in the sense of not wanting to make promises that may not be able to be kept. The Rust developers want GAT--or something analogous to GAT--and much work has been put in towards that goal (work that will have been useful even without GAT), and at this juncture there's no foreseen theoretical impediments; however, that's not to say that some unforeseen impediment won't yet arise. Such a thing happened with specialization, which has been in the works for much longer (current status: https://github.com/rust-lang/rust/pull/68970), and the lesson has been to not incite expectation until you are extremely certain the promise will be able to be kept. As a mere half-informed bystander it seems that GAT not encountering the problems that specialization did, but don't take this as any sort of promise. :)
The neat thing about GAT is that it doesn't really increase the user-facing complexity of the language. Conceptually, users already need to understand generics, and they need to understand associated types. GAT, which allows users to use generics within associated types, doesn't feel like a new feature so much as it just feels like letting two existing features play nicely.
Certainly, but not in the sense of being uncertain about whether or not GAT are worthwhile, only in the sense of not wanting to make promises that may not be able to be kept. The Rust developers want GAT--or something analogous to GAT--and much work has been put in towards that goal (work that will have been useful even without GAT), and at this juncture there's no foreseen theoretical impediments; however, that's not to say that some unforeseen impediment won't yet arise. Such a thing happened with specialization, which has been in the works for much longer (current status: https://github.com/rust-lang/rust/pull/68970), and the lesson has been to not incite expectation until you are extremely certain the promise will be able to be kept. As a mere half-informed bystander it seems that GAT not encountering the problems that specialization did, but don't take this as any sort of promise. :)