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Cycle for Android
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Jaewe Heo
August 03, 2016
Programming
3
1.9k
Cycle for Android
functional and reactive programming in Kotlin
Jaewe Heo
August 03, 2016
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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