Now that's what I call inference!

Using Swift
1

Hey!!! I’ve just found out just how much Swift can infer from code.

Normally, a lazy property that simply creates an instance, looks like this:

  public lazy var itemAdded: ChangedEvent =
  {
    return ChangedEvent(sender: self)
  }()

But I’ve just found out you can do this:

  public lazy var itemAdded: ChangedEvent = .init(sender: self)

And even for more complex things like closures, you can do this:

  lazy var itemPropertyChangedClosure: PropertyChangeClosureType<itemT> =
  {
    return .init
    {
      sender, args in
      
      // …
    }
  }()

Now I can afford more time to have another cup of tea :sunglasses:

1 Like
2

Yes, Swift's inference capabilities are pretty powerful. For example, for people who really want to have more powerful ifs, could define static methods on Bool. (Whether you should is another question).

struct Person {
  let name: String
  var age: Int
}

extension Bool {
  static func canDrink(_ p: Person) -> Bool {
    return p.age >= 21
  }
}

let bob = Person(name: "Bob", age: 21)
let tom = Person(name: "Tom", age: 20)

if .canDrink(bob) {
  print("Get \(bob.name) a cold one")
}

if !.canDrink(tom) {
  print("\(tom.name) cannot drink")
}
1 Like
3

It would be interesting if giving some of it up could speed up compilation time significantly and still allow the language to steer you towards safer code constructs.