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
Cycle for Android
Search
Jaewe Heo
August 03, 2016
Programming
3
1.9k
Cycle for Android
functional and reactive programming in Kotlin
Jaewe Heo
August 03, 2016
Tweet
Share
More Decks by Jaewe Heo
See All by Jaewe Heo
Kotlin, Gradle and AWS SAM
importre
1
530
Kotlin-Flavored BuildScripts
importre
1
300
A tour of Standard Library
importre
0
100
Compose everything with rx & kotlin
importre
0
1.2k
Ready for Production
importre
2
310
Other Decks in Programming
See All in Programming
Web Components で実現する Hotwire とフロントエンドフレームワークの橋渡し / Bridging with Web Components
da1chi
3
1.8k
あなたの知らない「動画広告」の世界 - iOSDC Japan 2025
ukitaka
0
380
After go func(): Goroutines Through a Beginner’s Eye
97vaibhav
0
230
Go Conference 2025: Goで体感するMultipath TCP ― Go 1.24 時代の MPTCP Listener を理解する
takehaya
7
1.6k
CSC509 Lecture 03
javiergs
PRO
0
330
ネイティブ製ガントチャートUIを作って学ぶUICollectionViewLayoutの威力
jrsaruo
0
130
Swift Concurrency - 状態監視の罠
objectiveaudio
2
450
iOSアプリの信頼性を向上させる取り組み/ios-app-improve-reliability
shino8rayu9
0
150
Introducing ReActionView: A new ActionView-Compatible ERB Engine @ Kaigi on Rails 2025, Tokyo, Japan
marcoroth
3
920
エンジニアとして高みを目指す、 利益を生み出す設計の考え方 / design-for-profit
minodriven
23
12k
Serena MCPのすすめ
wadakatu
4
900
Playwrightはどのようにクロスブラウザをサポートしているのか
yotahada3
7
2.3k
Featured
See All Featured
Fight the Zombie Pattern Library - RWD Summit 2016
marcelosomers
234
17k
4 Signs Your Business is Dying
shpigford
185
22k
Understanding Cognitive Biases in Performance Measurement
bluesmoon
29
2.6k
GraphQLとの向き合い方2022年版
quramy
49
14k
The Straight Up "How To Draw Better" Workshop
denniskardys
237
140k
Building a Modern Day E-commerce SEO Strategy
aleyda
43
7.7k
YesSQL, Process and Tooling at Scale
rocio
173
14k
Connecting the Dots Between Site Speed, User Experience & Your Business [WebExpo 2025]
tammyeverts
9
580
Practical Tips for Bootstrapping Information Extraction Pipelines
honnibal
PRO
23
1.5k
[RailsConf 2023] Rails as a piece of cake
palkan
57
5.9k
Six Lessons from altMBA
skipperchong
28
4k
Faster Mobile Websites
deanohume
310
31k
Transcript
Cycle for Android Jaewe Heo · !iiid! · @importre Aug.
3, 2016 functional and reactive programming in Kotlin
import importre
About me • Android • Rx • Kotlin - Kotlin
Korea • Electron - Electron Korea • React - react-photonkit • Alfred workflows
alfred-mdi
alfred-pg
alfred-gi
alfred-hl
alfred-awe
alfred-tidy
Cycle for Android functional and reactive programming in Kotlin
Cycle.js http://cycle.js.org/
HCI (Human-Computer Interaction) two-way process
None
None
None
Mutual observation Reactive Programming
Two-way process val y = human(x)
Two-way process val y = human(x) val x = computer(y)
Two-way process val y = human(x) val x = computer(y)
?!
val x = computer(human(x))
Streams
Programming Foo Bar
Programming Foo Bar
Programming Foo Bar
Imperative Programming Foo Bar Proactive Passive Fooо Bar ࢚కܳ ߸҃ೡ
ࣻ . Barח ־о ೱਸ ח ݽܲ.
// This is inside the `Foo` module fun onNetworkRequest() {
// ... bar.incrementCounter() // ... } Example of the Imperative Programming
Barח ৻ࠗ ߮ী ߈ೞৈ न ࢚కܳ ҙܻೠ. Reactive Programming Foo
Bar Listenable Reactive Fooח ־ҳীѱ ೱਸ ח ݽܲ.
// This is inside the `Bar` module foo.addOnNetworkRequestListener { //
`this` is Bar this.incrementCounter() } Example of the Reactive Programming
Solve the cyclic dependency val y = human(x) val x
= computer(y)
Solve the cyclic dependency val proxyX = ReplaySubject.create<Any>() val y
= human(proxyX) val x = computer(y)
Solve the cyclic dependency val proxyX = ReplaySubject.create<Any>() val y
= human(proxyX) val x = computer(y) x.imitate(proxyX)
None
kotlin-cycle Cycle for Android (written in Kotlin)
Hello Example • ܴਸ ੍ (read) • ݫद ߸҃ (model)
• ݫदܳ ചݶী ࠁৈષ (write)
None
HelloActivity.kt class HelloActivity : BaseActivity() { override fun onCreate(savedInstanceState: Bundle?)
{ super.onCreate(savedInstanceState) setContentView(R.layout.activity_hello) Cycle.run(main, DomSource()) } private val main = { sources: Sources -> val change = sources.dom().select(helloEdit).textChanges() val model = change.map(::greeting) val view = model.map { message -> onUpdateView(message) } Sinks(DomSink(view)) } private fun onUpdateView(message: CharSequence) = { helloText.text = message } }
HelloActivity.kt class HelloActivity : BaseActivity() { override fun onCreate(savedInstanceState: Bundle?)
{ super.onCreate(savedInstanceState) setContentView(R.layout.activity_hello) Cycle.run(main, DomSource()) } private val main = { sources: Sources -> val change = sources.dom().select(helloEdit).textChanges() val model = change.map(::greeting) val view = model.map { message -> onUpdateView(message) } Sinks(DomSink(view)) } private fun onUpdateView(message: CharSequence) = { helloText.text = message } }
HelloActivity.kt class HelloActivity : BaseActivity() { override fun onCreate(savedInstanceState: Bundle?)
{ super.onCreate(savedInstanceState) setContentView(R.layout.activity_hello) Cycle.run(main, DomSource()) } private val main = { sources: Sources -> val change = sources.dom().select(helloEdit).textChanges() val model = change.map(::greeting) val view = model.map { message -> onUpdateView(message) } Sinks(DomSink(view)) } private fun onUpdateView(message: CharSequence) = { helloText.text = message } }
Kotlin-flavored Examples
HelloCycleActivity.kt class HelloCycleActivity : BaseActivity() { override fun onCreate(savedInstanceState: Bundle?)
{ super.onCreate(savedInstanceState) setContentView(R.layout.activity_hello) cycle { val change = dom.select(helloEdit).textChanges() val model = change.map(::greeting) model.map { message -> { helloText.text = message } } } } }
HelloCycleActivity.kt class HelloCycleActivity : BaseActivity() { override fun onCreate(savedInstanceState: Bundle?)
{ super.onCreate(savedInstanceState) setContentView(R.layout.activity_hello) cycle { val change = dom.select(helloEdit).textChanges() val model = change.map(::greeting) model.map { message -> { helloText.text = message } } } } }
Hello.kt fun greeting(name: CharSequence) = "Hello, $name!"
HelloTest.kt class HelloTest { @Test fun testGreeting() { val actual
= greeting("cycle") val expected = "Hello, cycle!" assertEquals(expected, actual) } }
BMI Example • ރޖѱ, ఃী ೠ ୡӝ ч ࢸ (properties)
• SeekBarܳ (read) • BMI ҅ • Ѿҗܳ ചݶী ࠁৈષ (write)
BmiActivity.kt cycle { val weightProps = Observable.just(Props(min = 40, max
= 140, value = 70)) val heightProps = Observable.just(Props(min = 140, max = 210, value = 170)) // Intent val (weightStream, heightStream) = intent(dom, heightProps, weightProps) // Model val stateStream = model(weightStream, heightStream, weightProps, heightProps) // View stateStream.map { state -> onUpdateView(state) } }
None
BmiActivity.kt private val intent = { dom: DomSource, heightProps: Observable<Props>,
weightProps: Observable<Props> -> val weightChangeStream = dom .select(weightSeekBar.apply { val props = weightProps.toBlocking().first() max = props.max - props.min progress = props.value - props.min }) .userChanges() val heightChangeStream = dom .select(heightSeekBar.apply { val props = heightProps.toBlocking().first() max = props.max - props.min progress = props.value - props.min }) .userChanges() Pair(weightChangeStream, heightChangeStream) }
BmiActivity.kt private val model = { weightChangeStream: Observable<Int>, heightChangeStream: Observable<Int>,
weightProps: Observable<Props>, heightProps: Observable<Props> -> Observable.combineLatest( weightChangeStream, heightChangeStream, weightProps, heightProps, ::calculateBmi) }
BmiActivity.kt private fun onUpdateView(state: State) = { unwrap(weightText, heightText, bmiText)
{ w, h, b -> w.text = "Weight: ${state.weight} kg" h.text = "Height: ${state.height} cm" b.text = "Bmi: ${state.bmi}" } nah { toast(R.string.error_undefined_views) } } kotlin-unwrap
Bmi.kt data class State(val weight: Int, val height: Int, val
bmi: Int) data class Props(val min: Int, val max: Int, val value: Int) fun calculateBmi(weight: Int, height: Int, weightProps: Props, heightProps: Props): State { val realHeight = height + heightProps.min val realWeight = weight + weightProps.min val heightMeters = realHeight * 0.01F val bmi = Math.round(realWeight / (heightMeters * heightMeters)) return State(realWeight, realHeight, bmi) }
REST Example • ࢜۽Ҋஜ (read) • ୡӝীח ࢜۽Ҋஜ হ ࢲߡ۽
ࠗఠ ؘఠܳ ੍যঠ ೣ • request(write) data -> response(read) data • Ѿҗܳ ചݶী ࠁৈષ (write) • ߡౡਸ ־ܴ (read) • షझܳ ڸ (write) https://jsonplaceholder.typicode.com/
UsersActivity.kt cycle { error = onError // Intent val usersStream
= api.getUsers() val refreshStream = dom .select(refreshView) .refreshes() .startWith(null as Void?) // Model val modelStream = Observable .combineLatest(usersStream, refreshStream) { users, refresh -> users } // View modelStream.map { users -> onUpdateView(users) } }
Extensions fun ImageView.loadUrl(imageUrl: String) = Picasso.with(context).load(imageUrl).into(this) fun Activity.toast(@StringRes id: Int)
= Toast.makeText(this, id, Toast.LENGTH_SHORT).show() fun Activity.toast(message: String) = Toast.makeText(this, message, Toast.LENGTH_SHORT).show() fun RecyclerView.ViewHolder.toast(message: String) = Toast.makeText(itemView.context, message, Toast.LENGTH_SHORT).show()
UserViewHolder.kt itemView.locationImage.loadUrl(url) itemView.nameText.text = user.name cycle { val emailChange =
dom.select(itemView.emailButton).clicks().map { ButtonType.EMAIL } val callChange = dom.select(itemView.callButton).clicks().map { ButtonType.CALL } val change = Observable.merge(emailChange, callChange) change.map { type -> show(user, type) } }
UserViewHolder.kt private fun show(user: User, type: ButtonType) = { toast(when
(type) { ButtonType.EMAIL -> user.email ButtonType.CALL -> user.phone }) }
Conclusion
Conclusion • ӭՔೞפ જӟೠؘ…
Conclusion • functional ೠо? • reactive ೠо? • productionী ਊ
оמೠо?
Conclusion • functional ೠо? • reactive ೠо? • productionী ਊ
оמೠо?
References
References - importre • https://github.com/importre/kotlin-cycle • https://github.com/importre/kotlin-unwrap • https://github.com/importre/ready-for-production •
Data class and Equality • Function Literals with Receiver • let, with, run, apply, use(using)
References - cycle.js • http://cycle.js.org/ • https://github.com/cyclejs-community/cycle-android
References - video • Unidirectional data flow architectures • What
if the user was a function?
val coWorker = true cycle { val change = dom
.select(toggle.apply { isChecked = true }) .checkedChanges() val model = change .map { onOff -> "উ٘۽٘ ѐߊܳ ݽभפ: $onOff" } .map { recruit -> "Riiid!\n$recruit" } model.map { message -> { checkText.text = message } } }
[email protected]
Thank you