alt Hacker News> The one thing you could say is that using some kind of token makes it dead simple to have different tokens. But that's really not something I run into often at all when using async.
It's valuable to library authors who can now write code that's agnostic of the users' choice of runtime, while still being able to express that asynchronicity is possible for certain code paths.
But that can already be done using async await. If you write an async function in Rust for example you are free to call it with any async runtime you want.