> Write a server that does communication or emulate select in Go in other languages.
I just did that - I've been working on a very similar thing to goduplicator (a mirroring proxy), however with an additional requirement that it must not add latency to the primary communication path, e.g must connect mirrors asynchronously and buffer data instead of waiting for a slow mirror.
I chose Rust and the resulting code has been at the same time simpler, faster and uses 3x fewer memory than the Go implementation. I have not only select!, but also things like join! or try_join! at my disposal, way simpler to use than channels and waitgroups.
Also looks like closing connections in Go is a mess. In Rust I just remove a connection value from the vector and I'm done. In Go they have to close them manually, but defer is quite useless in async code, where the connections are passed to a coroutine.
In Rust I can also interleave work concurrently on a single thread with async, avoiding synchronisation. In Go I'd have to spawn goroutines and then coordinate them through channels which would be both more complex, more costly to execute and more risky.
So IMHO Go is definitely an interesting language to write concurrent networking code in, but feels quite incomplete to me. You get products but no sum types, you get select (which is kinda sum for channels) but not join (which is an analogy of a product for channels). You get semi-automatic cleanup with defer, but it is tied to a lexical scope ignoring the fact that goroutines can outlive it.