Question

我有以下步骤：

trait BlackjackSteps {
    def gamerTakesTwoCards(gamerName:String): State[Deck, Gamer]
    def dealerTakesTwoCards: State[Deck, Dealer]
    def isBlackjack(gamer: Gamer, dealer: Dealer): Option[Player]
    def gamerDrawsCards(gamer: Gamer): State[Deck, Gamer]
    def dealerDrawsCards(dealer: Dealer, gamer: Gamer): State[Deck, Dealer]
    def determineWinner(gamer: Gamer, dealer: Dealer): Player

    def program(gamerName:String): State[Deck, Player] = for {
      gamer <- gamerTakesTwoCards(gamerName)
      dealer <- dealerTakesTwoCards
      //winner = isBlackjack(gamer, dealer)
      gamerFinal <- gamerDrawsCards(gamer)
      dealerFinal <- dealerDrawsCards(dealer, gamerFinal)
      winnerFinal = determineWinner(gamerFinal, dealerFinal)
    } yield  winnerFinal
  }

两个问题：

我如何获得gamerTakesTwoCards产生的Deck并将其传递给DealerTakesTwoCards？
isBlackjack可能会导致赢家，在这种情况下，我需要停止并返回赢家。如何更改上面的代码来做到这一点？

游戏：

玩家和发牌人
他们俩都抓了两张牌
如果没有21名获胜者
玩家保留抽奖牌直到17
最高得分不超过21分的玩家获胜！

在此处填写代码：https://bitbucket.org/jameskingconsulting/blackjack-scala/src/master/

编辑：

我已经不再理解了，只是弄清楚发生了什么：

def program(gamerName:String): State[Deck, Player] =
      gamerTakesTwoCards(gamerName).flatMap( gamer =>
        dealerTakesTwoCards.flatMap(dealer =>
          isBlackjack(gamer, dealer).fold(

            gamerDrawsCards(gamer).flatMap( gamerFinal =>
              dealerDrawsCards(dealer, gamerFinal).map( dealerFinal =>
                determineWinner(gamerFinal, dealerFinal)
              )
            )

          )(State.pure[Deck, Player])
        ))

Answer 1

无事可做。这就是重点。

在两种情况下，您都必须归还获胜者，无论isBlackjack返回None还是Some都是如此。无论哪种方式，您都必须返回State[Deck, Player]。例如，您可以在fold上使用Option，通过pure映射成功案例：

def program(gamerName:String): State[Deck, Player] = for {
  gamer <- gamerTakesTwoCards(gamerName)
  dealer <- dealerTakesTwoCards
  winner <- isBlackjack(gamer, dealer).fold(for {
    gamerFinal <- gamerDrawsCards(gamer)
    dealerFinal <- dealerDrawsCards(dealer, gamerFinal)
    winnerFinal = determineWinner(gamerFinal, dealerFinal)
  } yield winnerFinal)(State.pure[Deck, Player])
} yield winner

在程序中将State monad结果从一个步骤传递到另一个步骤+尽早停止

1 个答案: