我坚持实现tail递归foreach,reduce,map和toList函数,以实现二叉树的非常简单的实现.
sealed trait Tree[+A]
case object EmptyTree extends Tree[Nothing]
case class Node[A](value: A, left: Tree[A], right: Tree[A]) extends Tree[A]
object Tree {
def apply[A]: Tree[A] = EmptyTree
def apply[A](value: A): Tree[A] = Node(value, EmptyTree, EmptyTree)
def apply[A](value: A, left: Tree[A], right: Tree[A]): Tree[A] = Node(value, left, right)
def foreach[A](tree: Tree[A], f: (A) => Unit): Unit = {
//@tailrec
def iter[A](tree: Tree[A], f: (A) => Unit): Unit = tree match {
case EmptyTree =>
case Node(v, l, r) =>
iter(l, f) …