Thanks for the links, Steve, good to hear from someone on the Rust team. Somehow I automatically assumed Rust's executors sorta acted like a runtime, but now that you mention it, no reason they have to intercept syscalls. Anyway, I'm watching the rest of those videos now.

And yeah, there's always that extra step of handling thread cancellation yourself. I probably shouldn't have said it's purely about cooperative multitasking, but the docs on this (e.g. Microsoft's C# guide) still obscure these points a lot of the time.