It's not, your understanding of async in Zig is sound. I would even add that in the blog post in question (my post, the one ghoward is replying to in his) I don't even dare to describe Zig as colorless, in fact I say colorblind.
I don't really understand your crusade. I made this same observation in the past, it never satisfied you.
Your blog post is full of wrong information. I tried to explain to you what was wrong when you first posted it (so you can refer to those comments, if you want), but you keep seeing this as some kind of philosophical debate, and I have no interest in having this debate.
As I said to you already in the past, I just write software with Zig async and it works. Up to you what you want to do with your free time.
Accuracy is important in the marketplace of ideas, and especially in programming. Software is too buggy already, and it would only add more bugs to have programmers not understand the languages they use.
> I made this same observation in the past, it never satisfied you.
Yes, you made that same observation, and I appreciate that. But as @kbd so unintentionally demonstrated, people still believe that Zig is colorless. I want to dispel that notion completely.
I think you are not adding to the problem, and that is great. But the notion is still there.
> Your blog post is full of wrong information. I tried to explain to you what was wrong when you first posted it (so you can refer to those comments, if you want), but you keep seeing this as some kind of philosophical debate, and I have no interest in having this debate.
Here is all of the comments you made on Hacker News on the comments [1] about my blog post.
> That's exactly it. It just enables code reuse. You still have to think about how your application will behave, but you won't have to use an async-flavored reimplementaion of another library. Case in point: zig-okredis works in both sync and async applicatons, and I don't have to maintain two codebases.
> I thought using "colorblind" in the title of my original blogpost would be a clear enough hint to the reader that the colors still exist, but I guess you can never be too explicit.
and
> That's how it works in Zig. Calling an async function like this will also await it.
The closest thing to "explain[ing] to [me] what was wrong when [I] first posted it" is probably that first comment, which was in reply to
> I may be totally wrong with this assumption, but the way I understoo[d] Zig's color-less async support is that the compiler either creates a "red" or "blue" function body from the same source code based on how the function is called (so on the language level, function coloring doesn't matter, but it does in compiler output).
> The compiler still needs to stamp out colored function bodies because the generated code for a function with async support needs to look different - the compiler needs to turn the code into a state machine instead of a simple sequence).
> It's a bit unfortunate that red and blue functions appear to have a different "ABI signature", but I guess that's needed to pass an additional context pointer into a function with async support (which would otherwise be the implicit stack pointer).
(Original comment at [2] by flohofwoe.)
So if anybody explained anything, it's flohofwoe.
But flohofwoe's comment goes directly against the the language reference, so it's hard for me to believe.
The language reference says that sync functions are turned async if they call async functions. This implies virality of async on functions, which implies that many functions are definitely async-only.
If the compiler does something different, which it would have to if it actually makes two different versions of each function, then the language reference is wrong. Like I said, accuracy matters, so I would also like to see changes in the Zig language reference about this if that's the case.
> As I said to you already in the past, I just write software with Zig async and it works.
Yes, you write working software in Zig async, but you understand it better than most. People who go to the language reference and write based on that may not be able to write working software with Zig async as easily as you.
> The language reference says that sync functions are turned async if they call async functions. This implies virality of async on functions, which implies that many functions are definitely async-only.
> If the compiler does something different, which it would have to if it actually makes two different versions of each function, then the language reference is wrong. Like I said, accuracy matters, so I would also like to see changes in the Zig language reference about this if that's the case.
Thanks for confirming. So what does Zig actually do to execute async functions? Green threads in the background? An event loop? Is there documentation on the implementation?
When you set `const io_mode = .evented;` the stdlib observes that value and
- flips I/O functions to evented mode, both by setting the correct flags when creating, say, a socket, and also by having `suspend` and similar keywords in the winning branch of some comptime conditional statements, causing the functions in question to become async also in the language.
- instead of directly calling into main at program start, it starts an event loop and schedules main on it
This is all userland stuff based on a convention, none of this is ingrained in the programming language itself and it could very well be that in the future things will have to be done in a more explicit way.
Async functions are single frames (as opposed to being green threads).
It's not, your understanding of async in Zig is sound. I would even add that in the blog post in question (my post, the one ghoward is replying to in his) I don't even dare to describe Zig as colorless, in fact I say colorblind.