Future of VB and C# Lucian Wischik VB Language PM Microsoft

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History Managed Code Generics LINQ Co-evolution C#1, VB7 C#2, VB8 C#4, VB10 C#3, VB9

History Async Managed Code Generics LINQ Co-evolution C#1, VB7 C#2, VB8 C#4, VB10 C# vNext, VB11 C#3, VB9

History Async Managed Code Generics LINQ Co-evolution C#1, VB7 C#2, VB8 C#4, VB10 C# vNext, VB11 C#3, VB9 ??? “Roslyn”

History Async, Win8, CallerInfo VB: VBCore, Global, Iterators Managed Code Generics, EnC, My, partial, nullables, XML-comments LINQ, lambdas, XML literals, type inference, extensions Co-evolution, NOPIA, Dynamic/DLR, covariance C#1, VB7 C#2, VB8 C#4, VB10 C# vNext, VB11 C#3, VB9 ??? “Roslyn” ???

History Async, Win8, CallerInfo, VB: VBCore, Global, Iterators Managed Code Generics, EnC, My, partial, nullables, XML-comments LINQ, lambdas, XML literals, type inference, extensions Co-evolution, NOPIA, Dynamic/DLR, covariance C#1, VB7 C#2, VB8 C#4, VB10 C# vNext, VB11 C#3, VB9 ??? “Roslyn” ??? Async CallerInfo Roslyn

Async is a new, easier way to write connected apps. In the past… ● “Connected” has generally meant either a UI that freezes, or unmaintainable spaghetti code, or multithreading. C# and VB future: Async… ● Two new keywords: Await and Async in VB and C# ● A new Task-based design pattern for APIs, the "T.A.P." (Task Asynchronous Pattern) ● A new set of.NET Framework APIs Async CallerInfo Roslyn

Async is a new, easier way to write connected apps. In the past… ● “Connected” has generally meant either a UI that freezes, or unmaintainable spaghetti code, or multithreading. C# and VB future: Async… ● Two new keywords: Await and Async in VB and C# ● A new Task-based design pattern for APIs, the "T.A.P." (Task Asynchronous Pattern) ● A new set of.NET Framework APIs Async CallerInfo Roslyn Fundamentals Demo How it works Big picture

Async: Fundamentals

webClient.UploadString(uri); print("done"); webClient.UploadString(uri); print("done");

“A waiter’s job is to wait on a table until the patrons have finished their meal. If you want to serve two tables concurrently, you must hire two waiters.”

The following is from the Android dev blog. Can you spot the flaw? 1. “A good practice in creating responsive applications is to make sure your main UI thread does the minimum amount of work.” 2. “Any potentially long task that may hang your application should be handled in a different thread.” 3. “Typical examples of such tasks are network operations, which involve unpredictable delays.”

How best to explain the sequence of events in a restaurant with several tables? From the perspective of the patrons? or of the waiter?

Demo: async

This is the IL that’s emitted when you using async/await Async: How it works

async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } UI thread IOCP thread Async: How it works

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } UI thread IOCP thread Click [1/12] A button-click arrives on the UI queue

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } UI thread IOCP thread Click downTask [2/12] Invoke some functions; get back “downTask” from the API

async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } downTask async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } UI thread IOCP thread Click downTask » sc.Post{Κ1} [3/12] “await downTask” assigns a continuation and returns diggTask Κ1: diggTask

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } diggTask async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } UI thread IOCP thread Click downTask » sc.Post{Κ1} [4/12] “await diggTask” assigns a continuation and returns Κ1: Κ2: diggTask » sc.Post{Κ2}

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } UI thread IOCP thread Click rss [5/12] Network packet arrives with data downTask » sc.Post{Κ1} Κ1: Κ2: diggTask » sc.Post{Κ2}

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } UI thread IOCP thread Click rss sc.Post{Κ1(rss)} [6/12] Invoke downTask’s continuation with that data downTask » sc.Post{Κ1} Κ1: Κ2: diggTask » sc.Post{Κ2}

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } UI thread IOCP thread Click diggTask » sc.Post{Κ2} rss K1(rss) [7/12] Continuation is a “Post”, i.e. addition to the UI queue Κ1: Κ2: sc.Post{Κ1(rss)}

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } UI thread IOCP thread Click rss K1(rss) [8/12] UI thread executes K1, giving a result to the “await” Κ1: Κ2: sc.Post{Κ1(rss)} diggTask » sc.Post{Κ2}

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } UI thread IOCP thread Click rss K1(rss) [9/12] “Return story” will signal completion of task Κ1: Κ2: sc.Post{Κ1(rss)} diggTask » sc.Post{Κ2}

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } UI thread IOCP thread Click rss K1(rss) sc.Post(Κ2(story)) [10/12] Invoke diggTask’s continuation with data (by posting to UI queue) K2(story) Κ1: Κ2: sc.Post{Κ1(rss)} diggTask » sc.Post{Κ2}

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } UI thread IOCP thread Click rss K1(rss) sc.Post(Κ2(story)) K2(story) [11/12] Return from handling the K1 continuation Κ1: Κ2: sc.Post{Κ1(rss)}

async void button1_Click() { var diggTask = GetDiggAsync(); var digg = await diggTask; textBox1.Text = digg; } async Task GetDiggAsync() { var web = new WebClient(); var downTask = web.DownTaskAsync(" var rss = await downTask; var digg = XElement.Parse(rss).. ; return digg; } rss K2(story) Click K1(rss) UI thread IOCP thread sc.Post(Κ2(story)) Κ1: Κ2: [12/12] UI thread executes K2, giving a result to the “await” sc.Post{Κ1(rss)}

SINGLE-THREADED ASYNCHRONY AND CONCURRENCY is when we run asynchronous and concurrent tasks with NO additional threads (beyond those that the operating system already provides). No worries about mutexes &c. If you want extra threads, create them explicitly through Task.Run. SINGLE-THREADED ASYNCHRONY AND CONCURRENCY is when we run asynchronous and concurrent tasks with NO additional threads (beyond those that the operating system already provides). No worries about mutexes &c. If you want extra threads, create them explicitly through Task.Run.

 2008: Silverlight2: all its lengthy APIs are async  2010: [Feb] Windows Phone 7: all its lengthy APIs are async  2004: Asynchronous javascript (AJAX) hits big-time Async: big picture

 2008: Silverlight2: all its lengthy APIs are async  2010: [Feb] Windows Phone 7: all its lengthy APIs are async  2004: Asynchronous javascript (AJAX) hits big-time Async: big picture

 2008: Silverlight2: all its lengthy APIs are async  2010: [Feb] Windows Phone 7: all its lengthy APIs are async  2004: Asynchronous javascript (AJAX) hits big-time Async: big picture

 2008: Silverlight2: all its lengthy APIs are async  2010: [Feb] Windows Phone 7: all its lengthy APIs are async  2004: Asynchronous javascript (AJAX) hits big-time Async: big picture

TASK UNIFIES ALL THESE AREAS; ASYNC TIES THEM TOGETHER Use Async Functions to compose other tasks, for the “orchestration” of your app async Task DoWorkAsync() { try { string[] vidUrls = await ScrapeYoutubeAsync(url); // Network-bound Task t1 = DownloadVideoAsync(vidUrls(0)); // Start 2 downloads Task t2 = DownloadVideoAsync(vidUrls(1)); Video[] vids = await TaskEx.WhenAll(t1, t2); // Wait for both Video v = await MashupVideosAsync(vids(0), vids(1)); // CPU-bound await v.SaveAsync(textbox1.Text); // IO-bound } catch (WebException ex) { ReportError(ex); } } async Task DoWorkAsync() { try { string[] vidUrls = await ScrapeYoutubeAsync(url); // Network-bound Task t1 = DownloadVideoAsync(vidUrls(0)); // Start 2 downloads Task t2 = DownloadVideoAsync(vidUrls(1)); Video[] vids = await TaskEx.WhenAll(t1, t2); // Wait for both Video v = await MashupVideosAsync(vids(0), vids(1)); // CPU-bound await v.SaveAsync(textbox1.Text); // IO-bound } catch (WebException ex) { ReportError(ex); } }

Async CallerInfo Roslyn

CallerInfo will help with logging and in boilerplate code like INotifyPropertyChanged. void Log([CallerLineNumber] int line = 0, [CallerFilePath] string f = null, [CallerMemberName] string m = null) { Console.WriteLine(“{0}:{1} - {2}”, f, line, m); } Async CallerInfo Roslyn

Demo: CallerInfo

Async CallerInfo Roslyn

is about opening up the internals of the compiler to let everyone use the VB/C# languages in powerful ways. Async CallerInfo Roslyn

is about opening up the internals of the compiler to let everyone use the VB/C# languages in powerful ways. Async CallerInfo Roslyn

IL emit Binder Symbols Metaimp Parser

IL emit Binder Symbols Metaimp Parser Syntax tree API Symbol API Bind/flow API Emit API

IL emit Binder Symbols Metaimp Parser Syntax tree API Symbol API Bind/flow API Emit API Colorizer Formatter Outlining NavigateTo ObjBrowser GoToDef ExtractMeth QuickInfo Rename FindAllRefs IntellisenseEnC

IL emit Binder Symbols Metaimp Parser Syntax tree API Symbol API Bind/flow API Emit API Colorizer Formatter Outlining NavigateTo ObjBrowser GoToDef ExtractMeth QuickInfo Rename FindAllRefs IntellisenseEnC Interactive “REPL” window Script files (think.vbs) --.csx.vbx Use C#/VB as scripting languages for your app

Demo: Roslyn

Async CallerInfo Roslyn

Async Download the Async CTP Start making Task-returning APIs today CallerInfo Wait patiently… Roslyn Download the Roslyn CTP Give us feedback Async CallerInfo Roslyn

Module Module1 Sub Main() Dim robots = {"Number5", "Asimo", "Cylon"} Dim xml = Robot Status <%= Iterator Function() For Each r In robots Yield Robot reporting for duty Next End Function() %> Console.WriteLine(xml) End Sub End Module A parting word from VB: ITERATOR LAMBDAS! A parting word from VB: ITERATOR LAMBDAS!