scala - scala-错误: not found: value

Question

我刚在Scala工作，并试图通过一些简单的Scala工作表。

IDE是Intellij IDEA社区版本，并且操作系统Ubuntu 12.04已正确安装sbt。

但这会引发错误-error: not found: value
OI无法理解为什么会这样:

代码:

object session {
  1 + 2
  def abs(x: Double) = if (x < 0) -x else x         <== update this line
  def sqrtIter(guess: Double, x: Double): Double =
    if (isGoodEnough(guess, x)) guess
    else sqrtIter(improve(guess, x), x)

  def isGoodEnough(guess: Double, x: Double) =
    abs(guess * guess - x) < 0.001

  def improve(guess: Double, x: Double) =
    (guess + x / guess) / 2
  def sqrt(x: Double) = sqrtIter(1.0, x)
  sqrt(2)
  sqrt(4)
}

从屏幕右侧输出:

> res0: Int = 3

> <console>:8: error: not found: value isGoodEnough
             if (isGoodEnough(guess, x)) guess else sqrtIter(improve(guess, x), x)  
                 ^
  <console>:8: error: not found: value improve
             if (isGoodEnough(guess, x)) guess else sqrtIter(improve(guess, x), x)  
                                                             ^
> <console>:8: error: not found: value abs
             abs(guess * guess - x) < 0.001
             ^
> improve: (guess: Double, x: Double)Double

> <console>:7: error: not found: value sqrtIter
         def sqrt(x: Double) = sqrtIter(1.0, x)
                               ^    
> <console>:8: error: not found: value sqrt
                sqrt(2)
                ^

> <console>:8: error: not found: value sqrt
                sqrt(4)

有什么建议？

Answer 1

完整的错误消息是error: not found: value abs。找不到值“abs”。您需要math.abs。或者，您可以在需要这些数学函数之前在某处添加import math._。