Real world functional reactive programming
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My naive attempt at making FRP easy to digest.
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Real world functional reactive programming
- 2. Hello! I am Eric Polerecky You can find me at: @detroitpro
- 3. Functional Reactive Programming FRP is a HUGE topic; we are only going to scratch the surface. I’m not an expert in FRP
- 4. Is Rx (Reactive Extensions) right for me? Rx (Rx.NET) RxJs Bacon.JS Ruby RxJava RxCpp Python ReactiveCocoa reactivex.io rxmarbles.com introtorx.com The introduction to Reactive Programming you've been missing Paul Betts - Introduction to Rx reactiveui.readthedocs.org GitHub NetFlix Microsoft
- 5. Lets look a trivial example DEM O
- 6. OVERVIEW DEMO TIME! Define FRP Quick overview of functional programming Dive into reactive programming Why?!?!? DEMO TIME!
- 7. REACTIVE Reactive programming is an emerging discipline which combines concurrency and event-based and asynchronous systems. - Wikipedia
- 8. REACTIVE Reactive programming is programming with asynchronous data streams. - staltz TODO: Drink some water Get example of async data streams from audience
- 10. FUNCTIONAL Lambda Calculus Category Theory Mondas Functor Parametric Polymorphism
- 11. FUNCTIONAL ‘First Class’ Functions Pass functions into function Declarative Programming Compose methods together to create higher abstraction FRP uses come functional concepts but not all. FRP can be an introduction into functional programming. C# has functional concepts but is not a functional language.
- 12. FUNCTIONAL var even = numberRepository() .Select(x => x + 1) .Where(x => x % 2 == 0) .OrderByDescending(x=>x); linq is functional in nature pass functions into ‘functions’ operators methods can be composed
- 13. FUNCTIONAL ‘First Class’ Functions Pass functions into function Declarative Programming Compose methods together to create higher abstraction Immutable Data We don’t change data, we project (select) it into new formats FRP only really uses a small subset of functional concepts. The reactive part of FRP is more more complex and mind bending.
- 14. REACTIVE Reactive programming is programming with asynchronous data streams. - staltz TODO: Drink some water Get example of async data streams from audience
- 15. REACTIVE Click Click: async - if it happens, it will happen in the future. Examples of async data streams: click, message queue, mouse move. FRP is CONSTRUCTS for programming with async data streams.
- 16. REACTIVE variables user input properties caches lists Things that are not async data streams; but should have been and can be made into async data streams. Anything that could change (mutate) it’s value
- 17. REACTIVE twitter feed directory searching web service calls keyboard input file changed Twitter feed as data stream When you start thinking about async data streams. EVERYTHING BECOMES AN ASYNC DATA STREAM! list scroll video processing mouse move queues messaging
- 18. REACTIVE twitter feed directory searching web service calls keyboard input file changed This mental shift is the hardest part of FRP. list scroll video processing mouse move queues messaging
- 19. REACTIVE IObservable<T> and IObserver<T> Sometime, in the future, someone is going to give me data, how do I reason about it IEnumerable<T> and IEnumerable<T> I want all the data now! or I’ll stand here and wait, no one can do anything until I get my data!
- 20. REACTIVE IObservable<T> and IObserver<T> Sometime, in the future, someone is going to give me data, how do I reason about it IEnumerable<T> and IEnumerable<T> I want all the data now! or I’ll stand here and wait, no one can do anything until I get my data!
- 21. REACTIVE Events should have been lists FRP is commonly called: Linq to events
- 22. REACTIVE IObservable<T> Linq to events + Time!
- 23. REACTIVE Reactive programming is turning everything into an asynchronous data stream and programming with asynchronous data streams. - Eric Polerecky aka: detroitpro TODO: Drink some water Get example of async data streams from audience
- 24. WHY? event soup async / await everywhere! test-ability control time and space!
- 25. Lets look a non-trivial example DEM O
- 26. DECLARATIVE PROGRAMMING Higher abstraction, describe what you want
- 27. Let’s talk about declarative programming <h2>Hello</h2>
- 28. Let’s talk about declarative programming var even = numberRepository() .Select(x => x + 1) .Where(x => x % 2 == 0) .OrderByDescending(x=>x);
- 29. “ Expresses the logic of a computation without describing its control flow = Declarative Programming
- 30. What is a monad? MyObservable //event args come in, I don’t care from where .Select(x => x.FullPath) //transform data stream .Do(ZipFile) //the business logic that needs to happen .Catch<string,Exception>(...) .Retry(3) //cross cutting concerns removed from logic .Buffer(2) //bend time and space .Subscribe(); //make it so
- 32. “ Functional Reactive Programming = IObservable + Declarative Programming
- 33. “ Functional Reactive Programming is to events, lists and properties what Inversion of Control is to dependencies
- 34. WHEN Lets understand when to use Functional Reactive Programming
- 36. Desktop/Mobile/UI responsive UI anywhere that is stateful even the world wide web Incoming Data events (click events) streams of data (sensors) http file system
- 37. Let’s review what we learned about FRP ■ Reverse the flow of data ■ Declarative (higher level abstraction) ■ Linq to events ■ Good for when you would work with events ■ Good for when you have state (not request-response) ■ Reactive libraries are available in every language ■ Rx is on nuget (Rx-Main)
- 38. Thanks! Any questions? You can find me at: @detroitpro
Editor's Notes
- FRP is not pure functional programming. Functional programming in C# is not pure functional programming.
- Show a directory searcher with retry and junk. https://gist.github.com/detroitpro/204b9874c07817fd2bea
- Pass functions into functions Compose/chain functions
- Pass functions into functions Compose/chain functions
- Pass functions into functions Compose/chain functions
- Show a directory searcher with retry and junk. https://gist.github.com/detroitpro/204b9874c07817fd2bea
- focused on describing how a program operates.
- HTML (and XAML) is an example of declarative programming, we describe what we want, the rendering engine is responsible for display/layout.
- We reverse the flow of the caller, decouple the side-effects
- We build up a linq query, but nothing happens until the console.writeline. If we remove the foreach and console.writeline no items are pulled out of the enumerable.range. This (building up monads) is a concept from functional programming. This (passing lambdas) is also a concept from functional programming. GetEnumerator is called on the list of items until it is complete. What we have here is a pull based system. Our programming is pulling items out of the list, filtering on them (that’s cool) and acting on some of them.