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

Rx is a library for composing asynchronous and event-based programs using observable collections. Queries? LINQ? Too hard today…

You could get stuck C# 4.0 covariance

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

Source:

Reversing arrows… Input becomes output and vice versa Making a U-turn in synchrony

C# didn’t borrow Java checked exceptions

IDisposable ( & ) IEnumerator GetEnumerator( void ); We really got an enumerator and a disposable

void IEnumerator IEnumerableDual IEnumerable ) GetEnumerator( Set Will only dualize the synchrony aspect

This is an output too

Discrete domain with true and false

If you got true, you really got a T T

If you got false, you really got void void

(T | void | Exception) MoveNext( void But C# doesn’t have discriminated unions… Let’s splat this into three methods instead! But C# doesn’t have discriminated unions… Let’s splat this into three methods instead! Got IEnumeratorDual IEnumerator IEnumeratorDual>); IEnumerator x);

Source:

Used to detach the observer… Do you really know C# 4.0?

(*) Visit

You could get flooded C# 4.0 contravariance

Environment MoveNext Got next? Application OnNext Have next! IEnumerable IEnumerator IObservable IObserver Interactive Reactive

OnCompleted OnNext OnError new int[0] new[] { 42 } Throwing iterator Iterator that got stuck Notion of time

OnNext(0) OnNext(1) OnNext(2) yield 0 yield 1 yield 2

Hypothetical anonymous iterator syntax in C# Synchronous Asynchronous A variant with time notion exists (GenerateWithTime)

C# doesn’t have anonymous interface implementation, so we provide various extension methods that take lambdas. C# 4.0 named parameter syntax

F10F10

F10F10

F5F5

Breakpoint got hit

Lack of composition Resource maintenance?

Can define operators Resource maintenance!

Lack of composition Exceptions?Exceptions? Synchronous completion? Cancel?Cancel? State?State?

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

input.SelectMany(term => lookup(term))

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

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

// Alternative approach for composition using: // IObservable Switch (IObservable > sources) var res = (from term in input select lookup(term)).Switch(); Very local fix Hops from source to source

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

Rx is a library for composing asynchronous and event-based programs using observable collections. Queries! LINQ! Way simpler with Rx