Simulate the by-name type in Scala

A function can receive an arg of the type => A as in

    def add1(x: => Int): Int = {
      x + 1
    }

But how do you return such a type in a function? The answer is that you can’t. But you can come up with something similar:

  case class Lazy[T](f: () => T) extends (() => T){
    lazy val v = f()
    def apply(): T = v
  }
  def add1(x: Lazy[Int]): Int = {
    x() + 1
  }
  add1(Lazy(() => 5))