Five Unbelievable Secrets of Reactive Programming the Experts Don't Want You to Know!

Totally non-clickbaity article about lessons learned from reactive programming. Presented at Playgrounds, Melbourne, February 24, 2917.

1. @gregheo
2. FIVE ✋ Of Reactive Programming Unbelievable! Secrets The Experts Don’t Want YOU To Know!
4. $ You already know it!
5. Data flows Propagation of change
6. ' Sequences!
7. A type that provides sequential, iterated access to its elements. Sequence
8. A type that provides sequential, iterated access to its elements. Sequence
9. A type that provides sequential, iterated access to its elements. Sequence
10. Sequence indexable single direction unbounded?
12. View
 controller (x, y) Game
 controller Square View Move index
13. SEQUENCES SEQUENCES EVERYWHERE
14. ) Small pieces of logic
15. View
 controller (x, y)
16. .map({ (point: NSPoint) -> Int in for (i, squareView) in squareViews.enumerated() { if squareView.frame.contains(point) { return i } } }) vc.rx_mouseClicks an observable (aka a sequence) 0 1 2 3 4 5 6 7 8
17. View
 controller (x, y) Game
 controller Square index Square index
18. Game
 controller View
 controller (x, y) Square index
20. * Declarative style
21. View
 controller (x, y) Game
 controller Square View
 controller Result index View Move
22. gameController.resultObservable .subscribe(onNext: { moveResult in switch moveResult { case .win(let winner): let alert = NSAlert()
 // Show alert for winner case .draw: let alert = NSAlert()
 // Show alert for draw case .success(nextPlayer: player):
 // ... case .invalid(nextPlayer: player): // ... } })
23. gameController.moveObservable .subscribe(onNext: { singleMove in squareViews[singleMove.square].squareState = singleMove.player }) 0 1 2 3 4 5 6 7 8
24. View
 controller (x, y) Game
 controller Square View
 controller Result index View Move
25. + Testable code
27. Game
 controller Square index (Int) Result
28. Game
 controller let moves: [Int] = [1, 3, 52, 4] [.success(nextPlayer: .nought), .success(nextPlayer: .cross), .success(nextPlayer: .nought)] .invalid(nextPlayer: .cross),
29. [.success(nextPlayer: .nought), .success(nextPlayer: .cross), .success(nextPlayer: .nought)] .invalid(nextPlayer: .cross), XCTAssertEqual( , expected)
31. Data flows Propagation of change
32. 1. You already know it 2. Sequences everywhere 3. Small pieces of logic 4. Declarative style 5. Testable code
34. so reactive very sequence much declarative such testable wow
35. so reactive very sequence much declarative such testable wow
36. feedback gregheo.com