Switching on optional types

matrix.swift

let o1nil: Int? = nil
let o1: Int? = 1

func switcher(_ a: Int?, _ b: Int?) {
  switch (a, b) {
  case (nil, nil):
    print("nothing")
  case (let thing?, nil):
    print("lhs", thing)
  case (nil, let thing?):
    print("rhs", thing)
  case (let left?, let right?):
    print(left, right)
  }
}

switcher(o1nil, o1nil) // nothing
switcher(o1, o1nil) // lhs 1
switcher(o1nil, o1) // rhs 1
switcher(o1, o1) // 1 1

I wrote a blogpost on this: https://basthomas.github.io/switches-and-cases