Zig's colorless async was purely solving the unergonomic calling convention, at the cost of knowing if a function is async or not (compiler decides, does not give any hints and if you get it wrong then that's UB).
Arguably the main problem with async is that it is unergonomic. You always have to act like there were 2 types of functions, while, in practice, these 2 types are almost always self-evident and you can treat sync and async functions the same.
I don't really know Zig. How does it handle the common GUI thread pattern where you get lock free concurrency by funneling the async GUI code through the GUI thread?
When you know what functions and blocks are synchronous, you know the thread will not be yielded. If you direct async tasks to run on a single thread, you know they will never run concurrently. These together mean you can use that pattern to get lock free critical sections. You don't need to write thread-safe data structures.
If a function can yield implicitly, how do you have the control you need to pull this off?
It's a really common pattern in GUI dev so how does Zig handle that?
Zig's colorless async was purely solving the unergonomic calling convention, at the cost of knowing if a function is async or not (compiler decides, does not give any hints and if you get it wrong then that's UB).
Arguably the main problem with async is that it is unergonomic. You always have to act like there were 2 types of functions, while, in practice, these 2 types are almost always self-evident and you can treat sync and async functions the same.