Swift doesn't have async/await

Originator:dan.abramov
Number:rdar://17172652 Date Originated:06.05.14
Status:Open Resolved:
Product:Developer Tools Product Version:6
Classification: Reproducible:
 
Summary:
Getting asynchronous programming right is hands-down the hardest thing in developing modern apps today. C# simplified the hell out of this with async/await. JS is not too far behind with yield and coroutines already in Node v 0.11, and async/await coming in ES7. That Swift doesn't support this feature is a big disappointment to me, but I'm hoping it's planned.

See http://tirania.org/blog/archive/2013/Aug-15.html (Callbacks as our Generations' Go To Statement)

“Our intellectual powers are rather geared to master static relations and that our powers to visualize processes evolving in time are relatively poorly developed. For that reason we should do (as wise programmers aware of our limitations) our utmost to shorten the conceptual gap between the static program and the dynamic process, to make the correspondence between the program (spread out in text space) and the process (spread out in time) as trivial as possible.”

Dijkstra

Steps to Reproduce:
1. Try to write a decent app with async calls

Expected Results:
    try {
        Busy = true;
        UpdateUIStatus ("Taking a picture");
        var picker = new Xamarin.Media.MediaPicker ();
        var mFile = await picker.TakePhotoAsync (new Xamarin.Media.StoreCameraMediaOptions ());
        var tagsCtrl = new GetTagsUIViewController (mFile.GetStream ());
        // Call new iOS await API
        await PresentViewControllerAsync (tagsCtrl, true);
        UpdateUIStatus ("Submitting picture to server");
        await PostPicToServiceAsync (mFile.GetStream (), tagsCtrl.Tags);
        UpdateUIStatus ("Success");
    } catch (OperationCanceledException) {
        UpdateUIStatus ("Canceled");
    } finally {
        Busy = false;
    }

Actual Results:
https://o.twimg.com/1/proxy.jpg?t=FQQVBhhUaHR0cDovL2YuY2wubHkvaXRlbXMvMEcwaDFxMTUyZDFVMHEyMjBXMWgvSW1hZ2UlMjAyMDEzLjA4LjA4JTIwMTElM0E1MyUzQTI0JTIwUE0ucG5nFAQWABIA&s=QI9GeZLSgLIb5f5fHpX911kqiOAAqp-0XmZ0fbgSGUk

Comments

Duplicate filed.

By mike.akers at July 8, 2014, 9:56 p.m. (reply...)

Of course, we can implement it ourselves

It turns out that we can implement this feature ourselves:

https://alastairs-place.net/blog/2014/06/12/async-in-swift/

It isn't perfect, and inside the compiler there would likely be more scope for optimisations (like not making extra stacks all the time), but hey…

By alastair at June 12, 2014, 4:48 p.m. (reply...)

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