And then Result<T, E> only looks ok until you've experienced monads. And monads only look ok until you've experienced algebraic effects.

I believe that in a low-level, imperative language one should fully embrace call-by-push-value and make functions (computations) second class. Recovering first class functions should be an explicit, programmer-controlled step. This is what Effekt does to help with algebraic effects but I believe this is useful in general in a low-level language. In Rust functions are not truly first class. The language tries to gloss over this fact by hiding types behind traits, but this makes for sharp and pointy ergonomics. Better embrace second-class computations directly and offer good syntax for dealing with that. In Hylo references are second class. In combination with subscripts (coroutines) that makes for one possible way of introducing the necessary distinction, but I believe it is better and more natural to follow CBPV directly. In Futhark functions are also not first class. They seem to hide it better than Rust though.