The "traits can't have async" thing you're referring is at best a minor inconvenience or tiny optimization left on the table. This feature was intentionally pos

The "traits can't have async" thing you're referring is at best a minor inconvenience or tiny optimization left on the table. This feature was intentionally postponed. Traits can use async code, just not without boxing/dynamic dispatch. Given that other languages always box all their Promises/Tasks, Rust needing to do it in a couple of cases doesn't even put it at a disadvantage. To use async code in Rust you don't need to define any traits. For users of async traits the issue is invisible. For library authors that want their code to be both async and higher-order at the same time, the problem boils down to needing to add a macro to "polyfill" the feature for now, until "native" support comes later.