I think the main reason it doesn't exist is that go had no generics. It'd need to be another custom-generic type (Future[T] basically), and it would make it harder to pass around, just like channels. But since channels are generally intrusively-added, they aren't part of the return signature, so they avoid that generic-return issue. E.g. every "worker pool" accepts a `func()` and callers need to coordinate return values via channels, instead of needing to return a `func[T]()` reference which they have been unable to do until recently (to some degree at least).

Though they probably could've just said "use a Future[interface{}]", like they did for every other generic collection type.

Plus it'd take some of the emphasis off channels, and they seem to really not want to do that. If they were focused on usability instead of channels and select, they'd let us park on multiple mutexes just like channels, just like the runtime does internally a lot to implement all this... but no. Imagine a world where you could `select { case mut.Lock(): ...}`...