Read Writing High-Performance Swift Code from Swift compiler

Read Writing High-Performance Swift Code from Swift compiler.

Hm, final could by applied not only for classes but for methods and properties as well. Also private and fileprivate allow compiler infer final.

Interesting (despite ineffective for copying) way representing trees:

protocol P {}
struct Node: P {
  var left, right: P?
}

struct Tree {
  var node: P?
  init() { ... }
}

Brilliant idea to use Array as box just to benefit copy-on-write:

struct Tree: P {
  var node: [P?]
  init() {
    node = [thing]
  }
}

And this Box can replace the array in the code sample above:

final class Ref<T> {
  var val: T
  init(_ v: T) {val = v}
}

struct Box<T> {
    var ref: Ref<T>
    init(_ x: T) { ref = Ref(x) }

    var value: T {
        get { return ref.val }
        set {
          if !isKnownUniquelyReferenced(&ref) {
            ref = Ref(newValue)
            return
          }
          ref.val = newValue
        }
    }
}