Golang doesn't really have a sync context. It has one color because everything is async. The `go` operation is not comparable to `await`, rather it is comparable to spawning.
There’s a difference between sync and async code in Go, which is why you have all the normal threading primitives like mutexes, semaphores and blocking queues/channels.
The point is that functions themselves don’t come in sync or async flavors. Just like in Java.
I don't think the existence of mutexes, semaphores and queues/channels imply that there is a sync version of Go. You can totally use those primitives in asynchronous Rust too.
You call the queues blocking, but they aren't really in the sense of "blocking" usually used when talking about async in Rust. The Go runtime can and will preempt your Go code in the middle of waiting for a channel to run some other task, and this preemption is what makes it different from a blocking Rust channel. An async Rust channel will also make the calling function wait for messages when you await the receive method.
Basically my point is that because any Go code can be preempted at any point, that makes all Go code async. The language not making you type await on everything doesn't make it sync.
Well, my point is that go has the same concept of sync and async as Java. All Java code can be preempted at any point, thats how threads work. Go is more efficient at scale as it uses a more light weight unit of concurrency under the hood, but from a developers standpoint the code functions in the same way.
So if you think Go is pure-async, then Java is pure-async, as it has access to the same primitives as Go for dealing with concurrency. It’s just that Java, at the moment, spawns a full thread wheres Go does something more light weight under the hood.
Unless, of course, you define async as doing something with coroutines/fibers. But I’d argue that is an implementation detail.
In any case. We are essentially agreeing. Go avoids the two-color problem by having single colored functions. Wheras Rust, JS, C# have two-colored functions.
Well I define async as being able to run many things without spawning a separate thread for each thing, by somehow swapping the current task every so often.
Call it an implementation detail if you want, but in my eyes, it is what makes the difference between all-async and all-sync.
