xavierclements

package fpinscala.laziness

import Stream._

trait Stream[+A] {

  def foldRight[B](z: => B)(f: (A, => B) => B): B = // The arrow `=>` in front of the argument type `B` means that the function `f` takes its second argument by name and may choose not to evaluate it.
    this match {
      case Cons(h,t) => f(h(), t().foldRight(z)(f)) // If `f` doesn't evaluate its second argument, the recursion never occurs.
      case _ => z