hamishknight

Swift Concurrency Manifesto

Author: Chris Lattner

Contents

• Introduction
• Overall Vision
• Part 1: Async/await: Beautiful asynchronous APIs
• Part 2: Actors: Eliminating shared mutable state

hamishknight

struct Bar {
    init<T : LosslessStringConvertible>(_ f: T) {}
    init<T>(anything: T) {}
}

let b = Bar(UnicodeScalar(4))

hamishknight

func test(closure: () -> Void) -> () -> () {
    let localClosure : @noescape () -> Void = { closure() }
    localClosure()
    return localClosure // Invalid conversion from non-escaping function of type () -> Void to potentially escaping function type () -> ()
}

hamishknight

func test(closure: () -> Void) {
    let localClosure : @noescape () -> Void = { closure() }
    localClosure()
}

hamishknight

class Foo       {}
class Bar : Foo {}
class Baz : Foo {}

// if you remove the Foo type annotation, (bar, baz) is (Bar, Baz) will return true,
// as the compiler can statically check the type.
let bar : Foo = Bar()
let baz : Foo = Baz()

print((bar, baz) is (Bar, Baz)) // false

hamishknight

class Bar {
    let id : Int
    init(id: Int) { self.id = id }
}

class Foo {
    var bar : Bar
    init(bar: Bar) { self.bar = bar}
    
    func printBar() {

hamishknight

import Foundation
import QuartzCore

func benchmark(repeatCount: Int = 1, name: String = "closure", closure: () -> Void) {
    let d = CACurrentMediaTime()
    for _ in 0..<repeatCount {
        closure()
    }
    let d1 = CACurrentMediaTime()-d
    print("Benchmark of \(name) took \(d1) seconds")

hamishknight

import UIKit

struct ConstraintInfo {
    var attribute: NSLayoutAttribute = .left
    var secondAttribute: NSLayoutAttribute = .notAnAttribute
    var constant: CGFloat = 0
    var identifier: String?
    var relation: NSLayoutRelation = .equal
}