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Introduction to Functional Reactive

Programming

EliaszSawicki.com ( @EliSawic )

Functional Reactive Programming


Streams


Stream


Arrayslet values = [1, 2, 3, 4]let doubledValues = values.map { $0 * 2 }let higherThanTwo = values.filter { $0 > 2 }let sum = values.reduce(0, +)


Filter


Combine Latest


Chaining manipulations let names = nameField.reactive.text


Chaining manipulations names.filter { $0.characters.count >= 3}


Chaining manipulations names.filter { $0.characters.count >= 3} .map { return "Dear" + $0 }


Chaining manipulations let prefixedNames = names.filter { $0.characters.count >= 3} .map { return "Dear" + $0 }

let combined = combineLatest(prefixedNames, surnames)

combined.observeValues { prefixedNames, surname in print("Form input is \(prefixedNames) \(surname)") }


www.rxmarbles.com


ReactiveSwift


Events flow


Non-Terminating• Next


Terminating

• Completed

• Failed

• Interrupted (Reactive Cocoa)


This screen is a signal


Represents events over time


Observe



If you don't observe, it's gone


Observingpresentation.observeValues { idea in remember(idea: idea)}

presentation.observeCompleted { print("Time for a break")}


Signal producer


Represents a tasks


Does not start it's work if not asked


Producingpresenter.startWithSignal { (signal, _) in signal.observeValues { idea in print(idea) }

signal.observeCompleted { print("Time for a break") }}


Hot vs Cold


Signal SignalProducer

presentation.observeValues presentation.startWithValues


Signal SignalProducer

presentation.observeValues presentation.startWithValues

emits values all the time waits for your request


Properties


Bindings


Binding examplelet (slides, _) = Signal<Slide, NoError>.pipe()

label.reactive.text <~ slides.map { return "Slide: \($0.number)" }


Memory Management


Disposables


Free your memorylet disposable = signal.observeValues { value in ...}

deinit { disposable.dispose()}


FUNctional reactive programming


Mobile

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