Sorry, I'm just getting into this conversation late and am by no means experienced in the area, but why can't the one where you don't want the caller to wait for the result be spelled async -> Never? Theoretically, async -> Void means you're awaiting a result with only one possible value, but if you're not waiting at all, then there is truly no result, yes? ··· On Sun, Nov 12, 2017 at 9:27 AM, Yuta Koshizawa via swift-evolution < swift-evolution@swift.org> wrote: Sorry, I had got s...