Comparative Asynchronous Programming

Presented at Playgrounds Conf: http://www.playgroundscon.com/

Transcript

1. Comparative Asynchronous Programming
3. Agenda 1. Asynchronous programming is hard. 2. Swift already supports a few async methodologies. 3. Swift supports some other paradigms. 4. But lacks support for others.
4. Asynchronous Programming: Difficult and Subjective
5. “Normal” programming
6. let returnValue = someFunctionCall()
7. Asynchronous programming
8. Development is all about tradeoffs
9. let file = readFile() ... readFile() { file in ... }
10. Embrace Tradeoffs
11. Swift Has Async Built-in. Sorta.
12. Built-in Async Approaches
13. Grand Central Dispatch
14. NSOperationQueue / DRBOperationTree
15. POSIX Threads
16. Target / Action
17. Callbacks / Completion Handlers
18. logIn(with: credentials) { result in // Handle login success or failure }
19. Callback Hell
20. getCredentialsFromUser() { credentials in logIn(with: credentials) { result in // Handle login success or failure } }
21. getCredentialsFromUser() { credentials, error in if credentials { logIn(with: credentials) { login, error in if login { // Handle login success } else { // Handle error } } } else { // Handle error } }
22. (credentials: Credentials?) -> Void (credentials: Credentials?, error: Error?) -> Void (result: Result<Credentials>) -> Void
23. enum Result<T> { case success(T) case error(Error) }
24. Callback Heaven
25. Some Async Abstractions are Supported in Swift
26. Promises & Futures
27. getCredentialsFromUser() .flatMap { credentials in return login(with: credentials) } .onSuccess { login in // Handle login success } .onFailure { error in // Handle login error }
28. Functional Reactive Programming
29. getCredentialsFromUser() .flatMap { credentials in return login(with: credentials) } .on(next: { login in // Handle login success }, error: { error in // Handle login error })
31. gerstureRecognizer.rx .event .map { recognizer in return recognizer.location(in: recognizer.view) } .bind(to: circle.rx.center)
32. Actor Model
34. Actor Model
35. Some Async Abstractions are Impossible in Swift
36. Async / Await
37. async func logIn() -> Login { let credentials = await getCredentialsFromUser() return await logIn(with: credentials) }
38. Coroutines and Generator Functions
39. func fibGenerator*() -> Int { var i = 0, j = 1 repeat { let next = i + j yield next (i, j) = (j, next) } while true } fibGenerator() // returns 1 fibGenerator() // returns 2 fibGenerator() // returns 3 fibGenerator() // returns 5
40. Wrap Up 1. There’s no “right way” to do async programming. 2. Asynchronous abstractions built into Swift aren’t great. 3. There are some cool things you can do in Swift. 4. There are other cool things that you can’t do in Swift.