Rx is a library for composing asynchronous and event-based programs using observable collections.

Transcription

1 Slides license: Creative Commons Attribution Non-Commercial Share Alike See

2 Too hard today (f g)(x) = f(g(x)) Rx is a library for composing asynchronous and event-based programs using observable collections. Queries? LINQ? MSDN DevLabs.NET 3.5 SP1,.NET 4.0 Silverlight 3, Silverlight 4 JavaScript (RxJS) XNA 3.1 for XBOX and Zune Windows Phone 7

3 interface IEnumerable out IEnumerator Get C# 4.0 covariance interface IEnumerator out IDisposable bool void Move get You could get stuck

4 (Waiting to move next) C# 4.0 covariance moving on You could get stuck

5 Because the Dutch are (said to be) cheap A B A B A B A B

6 Because the Dutch are (said to be) cheap A B A B A B A B

7 The recipe to dualization Making a U-turn in synchrony Reversing arrows Input becomes output and vice versa

8 interface IEnumerable IEnumerator interface IEnumerator IDisposable bool void get

9 interface IEnumerable IEnumerator void interface IEnumerator IDisposable bool void void throws Exception get void C# didn t borrow Java checked exceptions

10 interface IEnumerable<T> IEnumerator<T> GetEnumerator(void); interface IEnumerator IDisposable bool void throws Exception void

11 interface IEnumerable<T> (IDisposable & IEnumerator<T>) GetEnumerator(void); interface IEnumerator We really got an enumerator and a disposable bool void throws Exception void

12 interface IEnumerable<T> IDisposable IEnumerator<T> ) GetEnumerator( void interface IEnumerator Will only dualize the synchrony aspect bool void throws Exception void

13 interface IEnumerableDual<T> Set IDisposable void IEnumerator interface IEnumerator bool void throws Exception void

14 interface IEnumerableDual IDisposable IEnumerator<T> x interface IEnumerator This is an output too bool void throws Exception void

15 interface IEnumerableDual IDisposable IEnumerator<T> x interface IEnumerator bool Exception void void Discrete domain with true and false

16 interface IEnumerableDual IDisposable IEnumerator<T> x interface IEnumerator T true false Exception void void If you got true, you really got a T

17 interface IEnumerableDual IDisposable IEnumerator<T> x interface IEnumerator void false Exception void If you got false, you really got void

18 interface IEnumerableDual IDisposable IEnumerator<T> x); interface IEnumerator<T> (T void Exception) MoveNext( void

19 interface IEnumerableDual IDisposable IEnumeratorDual<T>); interface IEnumeratorDual<T> Got void (T void Exception)); But C# doesn t have discriminated unions Let s splat this into three methods instead!

20 interface IEnumerableDual IDisposable IEnumeratorDual<T> interface IEnumeratorDual void void void Exception void

21 interface IObservable IDisposable IObserver<T> observer interface IObserver void void void Exception Source:

22 interface IObservable out IDisposable Do you really know C# 4.0? IObserver<T> observer Used to detach the observer interface IObserver in void void void Exception

23 interface IObservable out IDisposable IObserver<T> observer interface IObserver in void void void Exception (*) Visit

24 interface IObservable out IDisposable Subscribe IObserver interface IObserver in C# 4.0 contravariance void On void On Exception void On You could get flooded

25 Interactive MoveNext Application Got next? IEnumerable<T> IEnumerator<T> OnNext IObservable<T> IObserver<T> Have next! Reactive Environment

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27 OnCompleted.Empty<int>() new int[0] OnNext.Return(42) new[] { 42 } OnError.Throw<int>(ex) Throwing iterator.never<int>() Notion of time Iterator that got stuck

28 OnNext OnError OnCompleted.Range(0, 3) OnNext(0) OnNext(1) OnNext(2).Range(0, 3) yield 0 yield 1 yield 2

29 A variant with time notion exists (GenerateWithTime) Observable Hypothetical anonymous iterator syntax in C# new IEnumerable int for int yield return Asynchronous Console Synchronous foreach var in Console

30 IObservable int Observable int // Assume we introduce concurrency (see later) IDisposable C# 4.0 named parameter syntax Console "Next: " Console "Oops: " Console "Done" C# doesn t have anonymous interface implementation, so we provide various extension methods that take lambdas.

31 IObservable int Observable int // Assume we introduce concurrency (see later) IDisposable Console "Next: " Console "Oops: " Console "Done" Thread.Sleep(30000); // Main thread is blocked F10

32 IObservable int Observable int // Assume we introduce concurrency (see later) IDisposable Console "Next: "

33 IObservable int Observable int // Assume we introduce concurrency (see later) IDisposable Console "Next: " Console "Oops: " Console "Done" Thread.Sleep(30000); // Main thread is blocked F5

34 IObservable int Observable int // Assume we introduce concurrency (see later) Breakpoint got hit IDisposable Console "Next: " Console "Oops: " Console "Done" Thread.Sleep(30000); // Main thread is blocked

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36 .MouseMove args if ( == ) // I d like to raise another event Lack of composition -= /* what goes here? */ Resource maintenance?

37 IObservable<Point> Observable.FromEvent "MouseMove" var.where( ) Can define operators var.dispose() Resource maintenance!

38 Exceptions? FileStream File "data.txt" byte new byte new AsyncCallback int Cancel? // Do something with bs[0..bytesread-1] null State? Lack of composition Synchronous completion?

39 FileStream File "data.txt" Func IObservable< > Observable.FromAsyncPattern byte new byte // Do something with bs[0..bytesread-1]

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41 Cold.Return.Subscribe( ).Subscribe( ) Hot.FromEvent " "

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43 IScheduler.Return Scheduler.ThreadPool

44 duality.toobservable();.toenumerable() reactive.amb( )

45 .Return Scheduler.ThreadPool " ".ObserveOn(frm) " "

46 push based notion of time // Producing an IObservable<Point> using Select select.location // Filtering for the first bisector using Where where

47 Asynchronous request React TextChanged Reaction Reactive Reactor Data binding on UI thread

48 // IObservable<string> from TextChanged events var Observable EventArgs "TextChanged" var from in select TextBox TimeSpan // Bridge with the dictionary web service var new DictServiceSoapClient var Observable string DictionaryWord // Compose both sources using SelectMany var from in from in select input.selectmany(term => lookup(term))

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50 Re Rea Reac React Reactive Reacti Reactiv R Reactive Reaction Reactive Reactor input Service call 1 Service call 2 UI data binding

51 Re Rea Reac React Reactive Reacti Reactiv R Reactive Reaction Reactive Reactor input Service call 1 Service call 2 UI data binding Source:

52 Re Rea Reac React Reactive Reacti Reactiv R Reactive Reaction Reactive Reactor input Service call 1 Service call 2 UI data binding Source:

53 Re Rea Reac React Reactive Reacti Reactiv R Reactive Reaction Reactive Reactor input Service call 1 Take Until Service call 2 UI data binding Source:

54 Re Rea Reac React Reactive Reacti Reactiv R Reactive input Service call 1 Service call 2 UI data binding

55 // IObservable<string> from TextChanged events var Observable EventArgs "TextChanged" var from in select TextBox TimeSpan // Bridge with the dictionary web service var new DictServiceSoapClient var Observable string DictionaryWord // Compose both sources using SelectMany Very local fix var from in from in.takeuntil(input) select

56 // IObservable<string> from TextChanged events var Observable EventArgs "TextChanged" var from in select TextBox TimeSpan // Bridge with the dictionary web service var new DictServiceSoapClient var Observable string DictionaryWord // Alternative Compose both approach sources for using composition SelectMany using: // var IObservable<T> from Switch<T>(IObservable<IObservable<T>> in sources) var res = (from term in input.takeuntil(input) select select lookup(term)) Hops from source to source.switch();

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58 Fixed (MSIL) Homo-iconic AsQueryable AsQbservable Translatable (Expression trees) How? IQueryable<T> E.g. LINQ to SQL ToQbservable IQbservable<T> E.g. LINQ to PowerShell ToQueryable LINQ to *.* AsObservable AsEnumerable ToObservable IEnumerable<T> E.g. LINQ to Objects IObservable<T> E.g. LINQ to Events ToEnumerable Pull (interactive) Duality Push (reactive) What? Threads Worker pools Message loops Distributed

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60 Way simpler with Rx (f g)(x) = f(g(x)) Rx is a library for composing asynchronous and event-based programs using observable collections. Queries! LINQ! MSDN DevLabs.NET 3.5 SP1,.NET 4.0 Silverlight 3, Silverlight 4 JavaScript (RxJS) XNA 3.1 for XBOX and Zune Windows Phone 7

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