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Reactive Collections
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Aleksandar Prokopec
July 30, 2014
Programming
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190
Reactive Collections
Description of the reactive collections framework from the Scala 2014 workshop.
Aleksandar Prokopec
July 30, 2014
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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!