DIY your own Combine framework

Transcript

1. DIY your own Combine framework Basic Functional Reactive Programming concepts

   Li-Heng Hsu 許立衡 @ iPlayground 2019

2. – Apple documentation "The Combine framework provides a declarative Swift

   API for processing values over time."
3. None

4. Concepts • Builder pattern • map(_:) method

5. Builder pattern • For constructing instances • Like initializer, factory

   method… 1. Create a builder struct 2. Store construction info in it 3. Call its build() method to construct a product

6. URLComponents URL builder

7. Combine Subscription builder

8. Builder pattern Combine Builder Publisher Construction info Operator build() Subscriber

   Product Subscription Roles

9. CombineDIY.swift

10. map(_:) method • There are different worlds in code •

    World of Uncertainty, World of Plurality, World of Erroneous... • Instances in these worlds can't be manipulated normally

11. Optional World of Uncertainty

12. World of Uncertainty Cat? (Cat) -> Double (Cat?) -> Double?

    map(_:)
13. None

14. Imperative Functional Metaphor Unwrap values Stack operations Optional if let

    x = x { /* ... */ } x.map { x in /* ... */ } Collection for i in x { /* ... */ } x.forEach { i in /* ... */ } Result if case .success(let x) = result { /* ... */ } result.map { x in /* ... */ }

15. World of Plurality [Cat] (Cat) -> Double ([Cat]) -> [Double]

    map(_:)

16. World of Temporality Publisher<Cat> (Cat) -> Double (Publisher<Cat>) ->
 Publisher<Double>

    map(_:)

17. DIY map(_:)

18. Feedback Come find me! Twitter: @lihenghsu