Comment by anonymoushn

> Rust considered using those (and, at first, that was the project's direction). Ultimately, they went to the stackless operation model because stackfull coroutine requires a runtime that preempts coroutines (to do essentially what the kernel does with threads). This was deemed too expensive.

Stackful coroutines don't require a preemptive runtime. I certainly hope that we didn't end up with colored functions in Rust because of such a misconception.