From a net-effect standpoint, Rust's implementation of async/await is fairly similar to protothreads, which were used even on smaller AVR and MSP430 targets whe

From a net-effect standpoint, Rust's implementation of async/await is fairly similar to protothreads, which were used even on smaller AVR and MSP430 targets where rtos threads weren't practical. That being said, protothreads were implemented using wildly cursed C macros, and offered none of the safety guardrails that Rust has, nor the ergonomics, and had some insane constraints, like "you can't use local variables at all, only statics" because like rust, they were stackless coroutines that meant you would have no control of the stack across await points. If you were VERY CAREFUL, you could get the same lightweight concurrency with almost the same fundamental model. Woe be on you if you ever had to debug though. edit - here's a look at how protothreads were expanded: https://dunkels.com/adam/pt/expansion.html https://dunkels.com/adam/pt/expansion.html