[swift-evolution] [Concurrency] async/await + actors

[Chris Lattner]

> On Aug 18, 2017, at 6:04 PM, Yuta Koshizawa <koher at koherent.org> wrote:
> 
> Hi, I have a question about the proposed `async/await`.
> 
> Are `throws async` and `await try` allowed? I think we have three options.
> 
> 1. allows only `async throws`-`try await`
> 2. allows both `async throws`-`try await` and `throws async`-`await try` and does not distinguish them
> 3. allows both and distinguishes them like `Promise<Result<T>>` and `Result<Promise<T>>`
> 
> Although 3 is the most expressive, I think it is too complicated. In most cases we need only something similar to `Promise<Result<T>>`. To select 1 also makes it possible to support 3 in the future. So 1 seems a good choice to me.

I agree.  If we are going to keep “async” and “throws” as unrelated axes on a matrix, then there cannot be a relationship implied by the ordering.  “throws async” and “async throws” need to mean the same thing.

-Chris