Comment by your_sweetpea

I suspect the end goal is to have suspend/resume (or some analogue) be userspace standard library functions used to implement Io.Evented. It'll end up being a userspace implementation like you see with many of the C coroutine libraries floating around on GitHub (minicoro, llco, etc).

Edit: Looking at the working prototype of Io.Evented, this may not be true actually. Perhaps this is the domain of a 3rd-party library except with stackless coroutines?

Another thing you may want to pay attention to, however, are the current proposals for getting evented IO working on WASM -- namely, stackless coroutines as a language feature: https://github.com/ziglang/zig/issues/23446