learning scala Function Recursive Tail Call

可以使用scala库，可以从字面上看出是在调用 递归函数：

code

import scala.util.control.TailCalls._




  val arrayDonuts: Array[String] = Array("Vanilla Donut", "Strawberry Donut", "Plain Donut", "Glazed Donut")


  println("
Step : How to define a tail recursive function using scala.util.control.TailCalls._")
  def tailSearch(donutName: String, donuts: Array[String], index: Int): TailRec[Option[Boolean]] = {
    if(donuts.length == index) {
      done(None) // NOTE: done is imported from scala.util.control.TailCalls._
    } else if(donuts(index) == donutName) {
      done(Some(true))
    } else {
      val nextIndex = index + 1
      tailcall(tailSearch(donutName, donuts, nextIndex)) // NOTE: tailcall is imported from scala.util.control.TailCalls._
    }
  }



  println("
Step : How to call tail recursive function using scala.util.control.TailCalls._")
  val tailFound = tailcall(tailSearch("Glazed Donut", arrayDonuts, 0))
  println(s"Find Glazed Donut using TailCall = ${tailFound.result}") // NOTE: our returned value is wrapped so we need to get it by calling result

  val tailNotFound = tailcall(tailSearch("Chocolate Donut", arrayDonuts, 0))
  println(s"Find Chocolate Donut using TailCall = ${tailNotFound.result}")

resule:

Step : How to define a tail recursive function using scala.util.control.TailCalls._

Step : How to call tail recursive function using scala.util.control.TailCalls._
Find Glazed Donut using TailCall = Some(true)
Find Chocolate Donut using TailCall = None