[sunshowers]

You're absolutely right! The problem is that this has introduced many bugs in our experience at Oxide. If you've already fully internalized the idea that futures are passive and can be cancelled at any await point, the talk is just a bunch of details.

[alembic_fumes]

I see. Do you suppose that the origin of these bugs is more about the difficulty of reasoning about the execution of deep async stacks, or does it come down to the developers holding an incorrect mental model of the Rust futures in their minds?

I am asking because I've noticed that many developers with previous experience from "task-based" languages (specifically the JS/TS world) tend to grasp the basics of Rust async quickly enough, but then run into expectation-misalignment related problems similar to the examples that you used in your post. That in turn has made want to understand whether it is the Rust futures that are themselves difficult or strange, or whether it's a case of the Rust futures appearing simple and familiar, even though they are completely different in very subtle ways. I suppose that it's a combination of both.

[sunshowers]

Yeah, it's a combination of both in my experience. I think even to experienced async Rust programmers, things like Tokio mutexes being really hard to use correctly can be a bit surprising.

Also, as another comment on the thread points out [1], languages where futures are active by default can have the opposite problem.

[1] https://news.ycombinator.com/item?id=45467188