[kbd]

> I don't know enough Zig to know whether you can write a bit of code that says "either pull from this queue or that queue when they are ready"; if so, then yes they are an adequate replacement, if not, no they are not.

Thanks for giving me a reason to peek into how Zig does things now.

Zig has a generic select function[1] that works with futures. As is common, Blub's language feature is Zig's comptime function. Then the io implementation has a select function[2] that "Blocks until one of the futures from the list has a result ready, such that awaiting it will not block. Returns that index." and the generic select switches on that and returns the result. Details unclear tho.

[1] https://ziglang.org/documentation/master/std/#std.Io.select

[2] https://ziglang.org/documentation/master/std/#std.Io.VTable

[jerf]

Getting a simple future from multiple queues and then waiting for the first one is not a match for Go channel semantics. If you do a select on three channels, you will receive a result from one of them, but you don't get any future claim on the other two channels. Other goroutines could pick them up. And if another goroutine does get something from those channels, that is a guaranteed one-time communication and the original goroutine now can not get access to that value; the future does not "resolve".

Channel semantics don't match futures semantics. As the name implies, channels are streams, futures are a single future value that may or may not have resolved yet.

Again, I'm sure nothing stops Zig from implementing Go channels in half-a-dozen different ways, but it's definitely not as easy as "oh just wrap a future around the .get of a threaded queue".

By a similar argument it should be observed that channels don't naively implement futures either. It's fairly easy to make a future out of a channel and a couple of simple methods; I think I see about 1 library a month going by that "implements futures" in Go. But it's something that has to be done because channels aren't futures and futures aren't channels.

(Note that I'm not making any arguments about whether one or the other is better. I think such arguments are actually quite difficult because while both are quite different in practice, they also both fairly fully cover the solution space and it isn't clear to me there's globally an advantage to one or the other. But they are certainly different.)

[kbd]

> channels aren't futures and futures aren't channels.

In my mind a queue.getOne ~= a <- on a Go channel. Idk how you wrap the getOne call in a Future to hand it to Zig's select but that seems like it would be a straightforward pattern once this is all done.

I really do appreciate you being strict about the semantics. Tbh the biggest thing I feel fuzzy on in all this is how go/zig actually go about finding the first completed future in a select, but other than that am I missing something?

https://ziglang.org/documentation/master/std/#std.Io.Queue.g...

[SkiFire13]

Maybe I'm missing something, but how do you get a `Future` for receiving from a channel?

Even better, how would I write my own `Future` in a way that supports this `select` and is compatible with any reasonable `Io` implementation?