2. LINQ, Take TwoRealizing the LINQ to Everything Dream Bart J.F. De Smet Software Development Engineer Microsoft Corporation

3. What’s LINQ?A historical perspective 5 years ago Little recent innovation Where’s the cloud? Censored

4. Essential LINQLanguage Integrated Monads Why? What? How?

5. Could there be more? Essential LINQThe monadic Bind operator IEnumerable<T> IQueryable<T> new[]{ 42 } IEnumerable<T> SelectMany<T, R>(this IEnumerable<T> source,Func<T, IEnumerable<R>> selector) SelectMany Also see www.codeplex.com/LINQSQO for “Project MinLINQ”

6. Essential LINQMaybe monad (for fun and no profit) Null-propagating dot string s = name?.ToUpper(); One single library function suffices Syntactic sugar name.SelectMany( _ => _.ToUpper(), s => s) from _ in name from s in _.ToUpper() select s Compiler

7. Essential LINQ Bart J.F. De Smet Software Development Engineer Cloud Programmability Team demo

8. Query Providers RevisitedWhy do we have IQueryable<T>? Does it really have to be a runtime check? Implements IQueryable<T> varsrc = newQueryProvider<Product>(); varres = from p insrc wherep.Price > 100m groupp byp.Category; foreach(var p in res) Console.WriteLine(p); Compiles fine

9. Query Providers RevisitedLeveraging the query pattern varres = from p insrc wherep.Price > 100m groupp byp.Category; Syntactic sugar varres = src .Where(p => p.Price> 100m) .GroupBy(p => p.Category); No GroupBy“edge” Can be instance methods Select Where Source<T> Filtered<T> Projected<T>

10. Query Providers RevisitedTaking it one step further Recipe Method overloads Type state machine Operator overloads varres = fromtweet intwitter where tweet. == “Bart” From About From Location From == “LINQ” where tweet. About About About Location select tweet; Query “learns” From operator overloading “Has a” type classTwitter { publicTwitterByFromWhere(Func<TweetAboutFromLoc, FilterFrom> filter); // Other filter methods } classTwitterByFrom { publicTwitterByAboutFromWhere(Func<TweetAboutLoc, FilterAbout> filter); // Other filter methods // Fields with current filters } Custom syntax trees

11. Query Providers Revisited Bart J.F. De Smet Software Development Engineer Cloud Programmability Team demo

13. JavaScript (RxJS)

14. XNA 3.1 for XBOX and Zune

16. Asynchronous Data AccessEssential interfaces interfaceIObservable<outT> { IDisposableSubscribe(IObserver<T> observer);} interfaceIObserver<in T> { voidOnNext(T value); voidOnError(Exception ex); voidOnCompleted(); } Both interfaces ship in the .NET 4 BCL

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

18. IObservable<T> Asynchronous Data AccessIQbservable<T> interfaceIQbservable<outT> : IObservable<T> { ExpressionExpression { get; } TypeElementType { get; } IQbservableProvider Provider { get; } } interfaceIQbservableProvider { IQbservable<R> CreateQuery<R>(Expression expression); } We welcome semantic discussions. Extended role for some operators No Execute method

19. LINQ to WMI Events (WQL) Bart J.F. De Smet Software Development Engineer Cloud Programmability Team demo

20. Asynchronous Data AccessC# 5.0 and VB 11.0 “await” One versus many? IObservable<T> interface – many results Task<T> concrete class – one result Task<T> based language feature Rx bridge by implementing the “await pattern” IAsyncEnumerable<T>

21. Asynchronous Bridge for C# and VB “await” Bart J.F. De Smet Software Development Engineer Cloud Programmability Team announcing

22. Where execution happensIScheduler interface System.Concurrencyin System.CoreEx Introduction of concurrency interfaceIScheduler { DateTimeOffsetNow { get; } IDisposable Schedule(Action action); IDisposable Schedule(Actionaction, TimeSpandueTime);} ToObservable IObservable<T> IEnumerable<T> ToEnumerable Synchronous Asynchronous

23. Where execution happensIScheduler specifies “where” Imported TextBoxTextChangedevent var res = from word ininput.DistinctUntilChanged() .Throttle(TimeSpan.FromSeconds(0.5)) from words in lookup(word) select words; Asynchronous web service call Indicates where things run Use of scheduler to synchronize res.Subscribe(words => { lst.Items.Clear(); lst.Items.AddRange((fromwordinwords selectword.Word).ToArray());}); res.ObserveOn(newControlScheduler(frm)).Subscribe(words => { lst.Items.Clear(); lst.Items.AddRange((fromwordinwords selectword.Word).ToArray());});

24. Where execution happensIScheduler parameterization Baked in notion of “where”? Entry-point for the schema Custom schedulers could be very rich (e.g. server farm) varctx = new NorthwindDataContext(); var res = from product inctx.Products whereproduct.Price > 100m selectproduct.Name; Decoupled “what” from “where” foreach(varproduct inres.RemoteOn(newSqlScheduler(“server”))) // Process product

25. Where execution happensExpression tree remoting Rx .NET fromtickerinstocks whereticker.Symbol == “MSFT” selectticker.Quote Observable data source JSON serializer Retargeting to AJAX RxJS stocks .Where(function (t) { returnt.Symbol == “MSFT”; }) .Select(function (t) { returnt.Quote; })

26. Remoting of Query Operators Bart J.F. De Smet Software Development Engineer Cloud Programmability Team demo

27. LINQ to the unexpectedConstraint solving Non-persistent Model[ Decisions[Reals, SA, VZ], Goals[ Minimize[20 * SA + 15 * VZ] ], Constraints[ C1 -> 0.3 * SA + 0.4 * VZ >= 2000, C2 -> 0.4 * SA + 0.2 * VZ >= 1500, C3 -> 0.2 * SA + 0.3 * VZ >= 500, C4 -> SA <= 9000, C5 -> VZ <= 6000, C6 -> SA >= 0, C7 -> VZ >= 0 ] ] fromminctx.CreateModel(new { vz = default(double), sa = default(double) }) where 0.3 * m.sa + 0.4 * m.vz >= 2000 && 0.4 * m.sa + 0.2 * m.vz >= 1500 && 0.2 * m.sa + 0.3 * m.vz >= 500 where 0 <= m.sa && m.sa <= 9000 && 0 <= m.vz && m.vz <= 6000 orderby 20 * m.sa + 15 * m.vz selectm Cost / barrel Refinement % Max # barrels Min # barrels To compute call Solve

28. LINQ to the unexpectedJoining with reactive sources Observabledata sources fromcostSAinGetPriceMonitor("SA") fromcostVZinGetPriceMonitor("VZ") fromminctx.CreateModel(new { vz = default(double), sa = default(double) }) where0.3 * m.sa + 0.4 * m.vz >= 2000 && 0.4 * m.sa + 0.2 * m.vz >= 1500 && 0.2 * m.sa + 0.3 * m.vz >= 500 where0 <= m.sa && m.sa <= 9000 && 0 <= m.vz && m.vz <= 6000 orderbycostSA* m.sa + costVZ* m.vz selectm SelectMany Subscribe here! Parametersto decision

29. Theorem Solving using Z3 Bart J.F. De Smet Software Development Engineer Cloud Programmability Team demo

30. What’s LINQ?A futuristic perspective Next 5 years Scheduler Remoting Solvers Rx and Ix are here! Toolkits Async Censored

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