Go tech lead Russ Cox:

This post is about why we need a coroutine package for Go, and what it would look like.

With a post like this it usually means there will almost certainly be a new standard library package. But even more interestingly:

If we are to add coroutines to Go, we should aim to do it without language changes. That means the definition of coroutines should be possible to implement and understand in terms of ordinary Go code. Later, I will argue for an optimized implementation provided directly by the runtime, but that implementation should be indistinguishable from the pure Go definition.