Is there something like this but without concurrency? I don't need concurrency or multithreading, and most of my pain with Rust has come from the fact that it prevents me from doing things that I know are correct because it thinks my code will run in a multithreaded environment (it will not).

It seems like Yao's whole project is solving the concurrency problem.

I'm like, why not drop it entirely (if performance isn't one of the language's top priorities anyway)? What does keeping it gain that's so important? (Context: I don't understand concurrency and multithreading.)