小编Kor*_*uay的帖子

我已经开始在 Coursera 上学习 Scala 并且有一些关于squareRootGuess实现的问题如下

我正在尝试实施标准来过滤sqrtGuess定义中的准确猜测，如下所示，但它给了我堆栈溢出错误。

def sqrtGuess(x: Double): Stream[Double] = { 
  def nextGuess(guess: Double): Double = (guess + x / guess)/2

  def isSufficient(guess: Double): Boolean = math.abs(x - guess*guess)/x < 0.001

  def guesses: Stream[Double] = 
    1 #:: guesses.map(nextGuess).filter(isSufficient)

  guesses
}

但是，如果我们在外部定义 isSufficientsqrtGuess并应用于sqrtGuess流，效果会很好。

def sqrtGuess(x: Double): Stream[Double] = { 
    def nextGuess(guess: Double): Double = (guess + x / guess)/2
    def guesses: Stream[Double] = 
        1 #:: guesses.map(nextGuess)
    guesses
}

def isSufficient(guess: Double, x: …