To prove (or potentially disprove) my assertion that this is not just sugar,
how would you accomplish the following under the current proposal?
let a = async longCalculationA()
let b = async longCalculationB() //b doesn’t wait for a to complete
before starting
let c = async longCalculationC() //c doesn’t wait for a or b
let result = await combineCalculations(a: a, b: b, c: c) //waits until
a, b, and c are all available
(Note: this is using my version of async below which doesn’t use futures)
Thanks,
Jon
> On Aug 25, 2017, at 2:13 PM, Jonathan Hull via swift-evolution
> <[email protected]> wrote:
>
> I actually really like the idea of using ‘async' to start a computation in a
> non-blocking way. It is extremely common in real-world code to want to start
> a few computations/downloads at once in the background and then use the
> results together...
>
> I think full-fledged futures could be a framework thing added on top, but
> what I would really love to see at the language level is that using ‘async’
> just allows you to defer calling ‘await’. That is, you could get a value
> back from something called with async, but you would be forced to await that
> value before it could be used:
>
> var image = async downloadImage() //Image is type UIImage
> //Do something else here
> let size = await image.size //The compiler forces me to call await
> before I can actually use the value
>
> This looks somewhat similar to a future, but you can’t interact with it as a
> separate type of object. The value above is just a UIImage, but with a
> compiler flag/annotation that forces me to call await on it before it can be
> accessed/used. The compiler has a lot more freedom to optimize/reorganize
> things behind the scenes, because it doesn’t necessarily need to make an
> intermediate object.
>
> I don’t think this is just sugar. It adds expressivity and control for a set
> of very common use-cases which aren’t fully supported by await alone.
>
> Thanks,
> Jon
>
>
>> On Aug 24, 2017, at 4:40 AM, Trevör ANNE DENISE via swift-evolution
>> <[email protected] <mailto:[email protected]>> wrote:
>>
>> Hello Swift community,
>>
>> I was really interested by the recent Task-based concurrency manifesto and
>> Concrete proposal for async semantics in Swift.
>>
>> Looking at beginAsync() and Futures, I had an idea for a new syntax based on
>> the `async` keyword, I'd love to hear your feedback about this idea:
>> https://github.com/adtrevor/Swift-ideas/blob/master/New%20async%20keyword%20usage.md
>>
>> <https://github.com/adtrevor/Swift-ideas/blob/master/New%20async%20keyword%20usage.md>
>>
>> Would such a syntax make any sense?
>>
>> Thank you ! :)
>>
>>
>> Trevör
>> _______________________________________________
>> swift-evolution mailing list
>> [email protected] <mailto:[email protected]>
>> https://lists.swift.org/mailman/listinfo/swift-evolution
>
> _______________________________________________
> swift-evolution mailing list
> [email protected]
> https://lists.swift.org/mailman/listinfo/swift-evolution
_______________________________________________
swift-evolution mailing list
[email protected]
https://lists.swift.org/mailman/listinfo/swift-evolution
