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Real world functional reactive programming
FRP is about programming with asynchronous data streams declaratively. Reactive programming treats everything as an asynchronous data stream. FRP uses concepts from functional programming like immutable data and first class functions. The key abstraction in FRP is IObservable which represents a stream of events or values over time. FRP is useful for handling events, stateful applications, and incoming data streams from sources like the file system, sensors, or HTTP requests.
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Real world functional reactive programming
- 1.
- 2. Hello! I am EricPolerecky You can find me at: @detroitpro
- 3. Functional Reactive Programming FRP is aHUGE topic; we are only going to scratch the surface. I’m not an expert in FRP
- 4. Is Rx (ReactiveExtensions) 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 atrivial example DEM O
- 6. OVERVIEW DEMO TIME! Define FRP Quickoverview of functional programming Dive into reactive programming Why?!?!? DEMO TIME!
- 7. REACTIVE Reactive programming isan emerging discipline which combines concurrency and event-based and asynchronous systems. - Wikipedia
- 8. REACTIVE Reactive programming isprogramming with asynchronous data streams. - staltz TODO: Drink some water Get example of async data streams from audience
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- 11. FUNCTIONAL ‘First Class’ Functions Passfunctions 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 Passfunctions 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 isprogramming 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 thatare 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 servicecalls 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 servicecalls 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 havebeen lists FRP is commonly called: Linq to events
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- 23. REACTIVE Reactive programming isturning 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 anon-trivial example DEM O
- 26. DECLARATIVE PROGRAMMING Higher abstraction, describewhat you want
- 27. Let’s talk aboutdeclarative programming <h2>Hello</h2>
- 28. Let’s talk aboutdeclarative programming var even = numberRepository() .Select(x => x + 1) .Where(x => x % 2 == 0) .OrderByDescending(x=>x);
- 29. “ Expresses the logicof a computation without describing its control flow = Declarative Programming
- 30. What is amonad? 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
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- 32. “ Functional Reactive Programming = IObservable+ Declarative Programming
- 33. “ Functional Reactive Programming isto events, lists and properties what Inversion of Control is to dependencies
- 34. WHEN Lets understand whento use Functional Reactive Programming
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- 36. Desktop/Mobile/UI responsive UI anywhere thatis stateful even the world wide web Incoming Data events (click events) streams of data (sensors) http file system
- 37. Let’s review whatwe 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 canfind me at: @detroitpro
Editor's Notes
- #4 FRP is not pure functional programming. Functional programming in C# is not pure functional programming.
- #6 Show a directory searcher with retry and junk. https://gist.github.com/detroitpro/204b9874c07817fd2bea
- #7 Pass functions into functions Compose/chain functions
- #10 Pass functions into functions Compose/chain functions
- #11 Pass functions into functions Compose/chain functions
- #26 Show a directory searcher with retry and junk. https://gist.github.com/detroitpro/204b9874c07817fd2bea
- #27 focused on describing how a program operates.
- #28 HTML (and XAML) is an example of declarative programming, we describe what we want, the rendering engine is responsible for display/layout.
- #34 We reverse the flow of the caller, decouple the side-effects
- #38 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.