Those don't actually execute simultaneously in Javascript, though. In Javascript, C# and I suspect Java, each usage of await generates a state machine that can

Those don't actually execute simultaneously in Javascript, though. In Javascript, C# and I suspect Java, each usage of await generates a state machine that can _defer execution_. So while one function is blocked, another can continue to execute. The concept is the same in Rust, except in Rust a nested await does not generate a new state machine. The entire async operation just uses a single state machine. The reason Rust does this is because its priorities are different than these other languages. Rust is built around zero-cost abstractions because it is intended to be as fast as possible while still safe. That's one of many reasons why Rust is considered a systems language and Javascript is not. They're for different things. For more on how async in Rust works, I'd invite you to read the actual manual on the subject (linked from the announcement): https://rust-lang.github.io/async-book/06_multiple_futures/01_chapter.html https://rust-lang.github.io/async-book/06_multiple_futures/0...