Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Introduction to FRP
Search
Stratos Pavlakis
July 21, 2015
Programming
3
210
Introduction to FRP
An introduction to Functional Reactive Programming - presented at 9th GreeceJS meetup
Stratos Pavlakis
July 21, 2015
Tweet
Share
More Decks by Stratos Pavlakis
See All by Stratos Pavlakis
Intro to Remix
pavlakis
0
150
Gitting like a pro - Take 2.pdf
pavlakis
0
43
4th Virtual GreeceJS - Tech News
pavlakis
0
14
3rd Virtual GreeceJS - Tech News
pavlakis
0
14
PWAs: the Application Shell & the well of surprises
pavlakis
1
180
Error Handling in Javascript
pavlakis
1
180
Gitting like a Pro
pavlakis
1
230
Async Patterns & Paradigms in Javascript
pavlakis
4
290
Going Mobile
pavlakis
2
180
Other Decks in Programming
See All in Programming
『ドメイン駆動設計をはじめよう』中核の業務領域
masuda220
PRO
5
1k
ECMAScript、Web標準の型はどう管理されているか / How ECMAScript and Web standards types are maintained
petamoriken
3
390
僕が思い描くTypeScriptの未来を勝手に先取りする
yukukotani
9
2.4k
マルチモジュールにおけるテスト最適化
fxwx23
0
210
XStateでReactに秩序を与えたい
gizm000
0
730
Desafios e Lições Aprendidas na Migração de Monólitos para Microsserviços em Java
jessilyneh
2
150
Method Swizzlingを行うライブラリにおけるマルチモジュール設計
yoshikma
0
120
AndroidアプリのUIバリエーションをあの手この手で確認する / Check UI variations of Android apps by various means
tkmnzm
1
190
Scala におけるコンパイラエラーとの付き合い方
chencmd
2
430
Shinjuku.rb#95:心の技術書紹介
free_world21
1
110
Using Livebook to build and deploy internal tools @ ElixirConf 2024
hugobarauna
0
250
Ebitengineの1vs1ゲーム WebRTCの活用
ponyo877
0
380
Featured
See All Featured
Docker and Python
trallard
39
3k
Building a Scalable Design System with Sketch
lauravandoore
459
32k
Product Roadmaps are Hard
iamctodd
PRO
48
10k
KATA
mclloyd
27
13k
A Tale of Four Properties
chriscoyier
155
22k
Sharpening the Axe: The Primacy of Toolmaking
bcantrill
36
1.7k
I Don’t Have Time: Getting Over the Fear to Launch Your Podcast
jcasabona
26
1.9k
Design by the Numbers
sachag
277
19k
Fight the Zombie Pattern Library - RWD Summit 2016
marcelosomers
230
17k
How STYLIGHT went responsive
nonsquared
93
5.1k
Web Components: a chance to create the future
zenorocha
309
42k
Keith and Marios Guide to Fast Websites
keithpitt
408
22k
Transcript
Functional Reactive Programming in Javascript
whoami Stratos Pavlakis Workable UI Tech Lead
[email protected]
th3hunt FRP
newbie!
what’s FRP?
let’s begin with
http://www.reactivemanifesto.org/ Responsive Message Driven Resilient Elastic
sweet dreams
so better start with
reactive paradigm var b = 1, c = 1; var
a = b + c; // a == 2 b = 10; • // a == ? • // imperative paradigm => a == 2 • // reactive paradigm => a == 11
front end development is it synchronous or asynchronous?
• User Input • AJAX • Web Sockets / SSE
• Web Workers • Animations • Cross origin frame communication • Updating the DOM we deal with
• User Input • AJAX • Web Sockets / SSE
• Web Workers • Animations • Cross origin frame communication • Updating the DOM most are async!
tools we use
callbacks var el = document.getElementById("my-button"); el.addEventListener("click", function () { console.log(‘my
button was clicked’); });
promises $http(endpoint1) .get({q: ‘frp’}) .then(function (data) { console.log(‘We got data
back from ajax %s’, data); }) .then(function (data) { return $http(endpoint2).get({id: data.id}); })
generators in ES7 async(function main() { var result1 = await
request( "http://endpoint.1" ); var data = JSON.parse( result1 ); var result2 = await request( "http://endpoint.2?id=" + data.id ); var resp = JSON.parse( result2 ); console.log( "Value: " + resp.value ); })
problems • callback hell • try / catch (except for
generators) • memory leaks • reduced composability
event driven programming we react to events
is reason about event streams what we’re really trying to
do
any number of values Array over any amount of time
f(time) / async an event stream would be
first class citizen of FRP observable
Observer Iterator Gang of Four - Design Patterns ES6 EventEmitter
array VS event
array === collection
events === collection
collections are iterable
observable === collection + time
observable API var subscription = myObservable.subscribe(function (val) { console.log(‘Next: %s’,
val); });
from the EventEmitter? so… how is that different
we know when it’s done var subscription = myObservable.subscribe( onNext,
onError, onCompleted ); like promises
we got set operators • map • flatMap • reduce
• merge • concat • zip
more operators • debounce • buffer • skipUntil • flatMapLatest
• combineLatest • switch • retry
observables can model • mouse clicks • key presses •
scrolling • animations • AJAX Polling, Web Sockets • timers • even… constants
operators http://rxmarbles.com/
filter
debounce
distinctUntilChanged
takeUntil
example please!
mousedown.flatMap((md) => { var startX = md.offsetX, startY = md.offsetY;
return mousemove.map((mm) => { return { left: mm.clientX - startX, top: mm.clientY - startY }; }).takeUntil(mouseup); }).subscribe((pos) => { dragTarget.style.top = pos.top + 'px'; dragTarget.style.left = pos.left + 'px'; }); drag & drop
Autocomplete yes I know, the classic example
requirements • filter queries • throttle requests • retry (overcome
network glitches) • avoid duplicate requests • match results to latest query • abort no longer valid requests
keyup => results var keyPress = $('#search').keyupAsObservable(); .keyPress.map((ev) => {
return ev.target.value; }) .filter((text) => { return text.length > 3; }) .debounce(500) .distinctUntilChanged() .flatMapLatest(search.retry(3).takeUntil(keyPress)) .map((d) => { return d.response[1]; }) .subscribe(showResults, showError); throttling no duplicate requests filtering match/abort response/results
gets even better
things we can do • cancel (can’t do with Promises)
• be lazy until a subscriber subscribes (cold) • setup datasource on first subscription • teardown datasource on disposal
not convinced yet?
observable future • TC39 proposal to add to ES7 ◦
https://github.com/zenparsing/es-observable • Angular 2 first class support • ReactJS first class support
http://victorsavkin.com/post/108837493941/better-support-for-functional-programming-in
Rx in production
still... • steep learning curve • old habits die hard
• tricky to work with classic MV* • poor/difficult documentation (is getting better)
libraries
• Rx.js (port of Reactive Extensions to JS) • Bacon.js
• Kefir (faster bacon :)
origins
Microsoft Research • A Brief Introduction to ActiveVRML - Conan
Elliott • Functional Reactive Animations - Conan Elliott & Paul Hudak
resources • Fran Tutorial - http://conal.net/fran/tutorial.htm • Simply Reactive -
http://conal.net/papers/simply-reactive/ • Reactive Extensions - https://github.com/Reactive-Extensions/RxJS • BaconJS - https://baconjs.github.io/ • Async JavaScript with Reactive Extensions (Jafar Husain) ◦ https://www.youtube.com/watch?v=XRYN2xt11Ek • RxJS at Modern Web UI (Ben Lesh) ◦ https://www.youtube.com/watch?v=yk_6eU3Hcwo • http://www.slideshare.net/stefanmayer13/functional-reactive-programming-with-rxjs • https://gist.github.com/staltz/868e7e9bc2a7b8c1f754 • RxJSKoans - https://rxkoans.codeplex.com/ • RxMarbles - http://rxmarbles.com/ • Reactive programming and MVC (Aaron Stacy) ◦ http://aaronstacy.com/writings/reactive-programming-and-mvc/
None
Questions?