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
Reactive Collections
Search
Aleksandar Prokopec
July 30, 2014
Programming
0
190
Reactive Collections
Description of the reactive collections framework from the Scala 2014 workshop.
Aleksandar Prokopec
July 30, 2014
Tweet
Share
More Decks by Aleksandar Prokopec
See All by Aleksandar Prokopec
ScalaMeter in 2014
axel22
0
330
A Reactive 3D Game Engine in Scala
axel22
4
8.2k
ScalaBlitz
axel22
0
200
Work-stealing Tree Scheduler
axel22
1
74
ScalaMeter
axel22
0
130
Ctrie Data Structure
axel22
0
220
Parallel Collections Overview
axel22
0
110
Introduction to Scala
axel22
2
290
Other Decks in Programming
See All in Programming
猫と暮らすネットワークカメラ生活🐈 ~Vision frameworkでペットを愛でよう~ / iOSDC Japan 2025
yutailang0119
0
220
フロントエンド開発に役立つクライアントプログラム共通のノウハウ / Universal client-side programming best practices for frontend development
nrslib
7
3.9k
高度なUI/UXこそHotwireで作ろう Kaigi on Rails 2025
naofumi
4
3.5k
Pull-Requestの内容を1クリックで動作確認可能にするワークフロー
natmark
2
450
iOSエンジニア向けの英語学習アプリを作る!
yukawashouhei
0
170
タスクの特性や不確実性に応じた最適な作業スタイルの選択(ペアプロ・モブプロ・ソロプロ)と実践 / Optimal Work Style Selection: Pair, Mob, or Solo Programming.
honyanya
3
140
株式会社 Sun terras カンパニーデック
sunterras
0
220
開発者への寄付をアプリ内課金として実装する時の気の使いどころ
ski
0
350
GraphQL×Railsアプリのデータベース負荷分散 - 月間3,000万人利用サービスを無停止で
koxya
1
1.1k
アメ車でサンノゼを走ってきたよ!
s_shimotori
0
140
複雑化したリポジトリをなんとかした話 pipenvからuvによるモノレポ構成への移行
satoshi256kbyte
1
770
Introducing ReActionView: A new ActionView-Compatible ERB Engine @ Kaigi on Rails 2025, Tokyo, Japan
marcoroth
3
920
Featured
See All Featured
The Art of Programming - Codeland 2020
erikaheidi
56
14k
Building Flexible Design Systems
yeseniaperezcruz
329
39k
The Power of CSS Pseudo Elements
geoffreycrofte
79
6k
Facilitating Awesome Meetings
lara
56
6.6k
Optimising Largest Contentful Paint
csswizardry
37
3.4k
Automating Front-end Workflow
addyosmani
1371
200k
Fantastic passwords and where to find them - at NoRuKo
philnash
52
3.4k
[RailsConf 2023 Opening Keynote] The Magic of Rails
eileencodes
31
9.7k
Building a Modern Day E-commerce SEO Strategy
aleyda
43
7.7k
Visualizing Your Data: Incorporating Mongo into Loggly Infrastructure
mongodb
48
9.7k
Testing 201, or: Great Expectations
jmmastey
45
7.7k
Gamification - CAS2011
davidbonilla
81
5.5k
Transcript
1 Containers and Aggregates, Mutators and Isolates for Reactive Programming
Aleksandar Prokopec, Philipp Haller, Martin Odersky
Reactive Collections http://reactive-collections.com 2
Reactive 3
4
5 Observables (event streams)
6 Observables (event streams) • declarative val log = messages
.filter(_.length < 100) .scan(_ + “\n” + _)
7 Observables (event streams) • declarative val log = messages
.filter(_.length < 100) .scan(_ + “\n” + _) var log = “” def receive = { case s: String => if (s.length < 100) log = log + “\n” + s }
8 Actors • encapsulate mutable state
9 Actors • encapsulate mutable state var log = “”
def receive = { case s: String => if (s.length < 100) log = log + “\n” + s }
10 Reactive collections Isolate Reactive Channel Actor ? ActorRef ?
Observable Observable
11 Reactive values
Reactive[T] 12
val ticks: Reactive[Long] 13 ticks 1 1 2 2 3
3 4 4 60 60 61 61
ticks onEvent { x => log.debug(s”tick no.$x”) } 14 1
2 3 4 60 61 tick no.1 tick no.2 tick no.3 tick no.4 tick no.60 tick no.61 ...
ticks foreach { x => log.debug(s”tick no.$x”) } 15 1
2 3 4 60 61
16 for (x <- ticks) { log.debug(s”tick no.$x”) } Single-threaded!
17 Reactive combinators
for (x <- ticks) yield { x / 60 }
18
val seconds: Reactive[Long] = for (x <- ticks) yield {
x / 60 } 19
60 61 val seconds: Reactive[Long] = for (x <- ticks)
yield { x / 60 } 20 ticks 1 1 2 2 3 3 60 61 seconds 0 0 0 1 1 ticks seconds 0 0 0 1 1
val days: Reactive[Long] = seconds.map(_ / 86400) 21
val days: Reactive[Long] = seconds.map(_ / 86400) val secondsToday =
22
val days: Reactive[Long] = seconds.map(_ / 86400) val secondsToday =
(seconds zip days) { (s, d) => s – d * 86400 } 23
val angle = secondsInDay.map(angleFunc) 24
val angle = secondsInDay.map(angleFunc) val light = secondsInDay.map(lightFunc) 25
26
27 val rotate = keys a ↓ shift ↓ a
↑ shift ↑ pgup ↓ pgup ↑ keys
28 val rotate = keys.filter(_ == PAGEUP) a ↓ shift
↓ a ↑ shift ↑ pgup ↓ pgup ↑ keys pgup ↓ pgup ↑ filter
29 val rotate = keys.filter(_ == PAGEUP) .map(_.down) a ↓
shift ↓ a ↑ shift ↑ pgup ↓ pgup ↑ keys pgup ↓ pgup ↑ filter true false map
30 if (rotate()) viewAngle += 1 true false map
31 Signals
32 trait Signal[T] extends Reactive[T] { def apply(): T }
33 val rotate = keys.filter(_ == PAGEUP) .map(_.down) .signal(false) true
false map signal
34 val rotate: Signal[Boolean] = keys.filter(_ == PAGEUP) .map(_.down) .signal(false)
true false map signal
35 val rotate: Signal[Boolean] val ticks: Reactive[Long] ticks
36 val rotate: Signal[Boolean] val ticks: Reactive[Long] ticks rotate
37 val rotate: Signal[Boolean] val ticks: Reactive[Long] val viewAngle: Signal[Double]
= ticks rotate viewAngle
38 val rotate: Signal[Boolean] val ticks: Reactive[Long] val viewAngle: Signal[Double]
= ticks.scanPast(0.0) ticks rotate viewAngle
39 val rotate: Signal[Boolean] val ticks: Reactive[Long] val viewAngle: Signal[Double]
= ticks.scanPast(0.0) { (a, _) => if (rotate()) a + 1 else a } ticks rotate viewAngle
40
41 val velocity = ticks.scanPast(0.0) { (v, _) => }
val viewAngle =
42 val velocity = ticks.scanPast(0.0) { (v, _) => if
(rotate()) v + 1 } val viewAngle =
43 val velocity = ticks.scanPast(0.0) { (v, _) => if
(rotate()) v + 1 else v – 0.5 } val viewAngle =
44 val velocity = ticks.scanPast(0.0) { (v, _) => if
(rotate()) v + 1 else v – 0.5 } val viewAngle = velocity.scanPast(0.0)(_ + _)
45
46 Reactive mutators
47 class Matrix { def apply(x: Int, y: Int): Double
def update(x: Int, y: Int, v: Double) }
48 val screenMat: Signal[Matrix] = (projMat zip viewMat)(_ * _)
val invScreenMat = screenMat.map(_.inverse)
49 Reactive[immutable.Matrix[T]]
50 val screenMat: Signal[Matrix] = (projMat zip viewMat)(_ * _)
val invScreenMat = screenMat.map(_.inverse) (4*4*8 + 16 + 16)*4*100 = 64 kb/s
51 val screenMat = Mutable(new Matrix) (projMat, viewMat).mutate(screenMat) { (p,
v) => screenMat().assignMul(p, v) } val invScreenMat = Mutable(new Matrix) screenMat.mutate(invScreenMat) { m => invScreenMat().assignInv(m) }
52 Reactive collections
53
54 val selected: Reactive[Set[Character]]
55 val selected: ReactSet[Character]
56 trait ReactSet[T] extends ReactContainer[T] { def apply(x: T): Boolean
}
57 trait ReactContainer[T] { def inserts: Reactive[T] def removes: Reactive[T]
}
58 A reactive collection is a pair of reactive values
59 val selected = new ReactHashSet[Character]
60
61 val selected = new ReactHashSet[Character] val decorations = selected
.map(c => (c, decoFor(c)))
62 class ReactContainer[T] { self => def inserts: Reactive[T] def
removes: Reactive[T] def map[S](f: T => S) = new ReactContainer[S] { def inserts: Reactive[T] = self.inserts.map(f) def removes: Reactive[T] = self.removes.map(f) } }
63 val selected = new ReactHashSet[Character] val decorations = selected
.map(c => (c, decoFor(c))) .to[ReactHashMap]
64 val selected = new ReactHashSet[Character] val decorations = selected
.map(c => (c, decoFor(c))) .to[ReactHashMap]
65 val selected = new ReactHashSet[Character] val decorations = selected
.map(c => (c, decoFor(c))) .to[ReactHashMap]
66 val selected = new ReactHashSet[Character] val decorations = selected
.map(c => (c, decoFor(c))) .to[ReactHashMap]
67 val selected = new ReactHashSet[Character] val decorations = selected
.map(c => (c, decoFor(c))) .react.to[ReactHashMap]
68 val selected = new ReactHashSet[Character] val decorations = selected
.map(c => (c, decoFor(c))) .react.to[ReactHashMap]
69 val selected = new ReactHashSet[Character] val decorations = selected
.map(c => (c, decoFor(c))) .react.to[ReactHashMap]
70 val selected = new ReactHashSet[Character] val decorations = selected
.map(c => (c, decoFor(c))) .react.to[ReactHashMap]
71 Isolates
72 UI isolate class UI extends Isolate[UI.Message] { val frames
= source.filter(_ == UI.Frame) val exit = source onCase { case UI.Exit => exit() } } Source
73 UI Isolate Source AI Isolate Source Channel[AI.Message]
Channel[UI.Message]
74 Reactive collections Isolate Reactive Channel Actor ? ActorRef ?
Observable Observable
75 Thank you!