Oh, I see. The article is saying that async is required. I thought it was saying that parallelism is required. The way it's written makes it seem like there's a problem with the code sample, not that the code sample is correct.
> Unfortunately this code doesn’t express this requirement [of concurrency], which is why I called it a programming error
I gather that this is a quirk of the way async works in zig, because it would be correct in all the async runtimes I'm familiar with (e.g. python, js, golang).
My existing mental model is that "async" is just a syntactic tool to express concurrent programs. I think I'll have to learn more about how async works in zig.
This is an artifact of wanting to write async code in environments where "threads" and "malloc" aren't meaningful concepts.
Rust does have a notion of autonomous existence: tasks.
Golang for example doesn't have that trait, where the user (or their runtime) must drive a future towards completion by polling.
I suppose I conflated "asynchrony" (as defined in the article) and "async" as a syntax feature in languages I'm familiar with.