For Rust, pre-GAT, there was no way to “output” a type which could be “called” with further arguments (very fuzzy terminology, sorry, best I can do!) or maybe i

For Rust, pre-GAT, there was no way to “output” a type which could be “called” with further arguments (very fuzzy terminology, sorry, best I can do!) or maybe in other words, you could write functions which retuned values, but not new functions. Nowadays, GATs support a bigger subset of HKTs, but still not everything as I understand it. https://blog.rust-lang.org/2022/10/28/gats-stabilization.html https://blog.rust-lang.org/2022/10/28/gats-stabilization.htm...