实习笔记 12：Scala 学习笔记

1. parameters and return types

numerics, boolean, string, function

example:

def abs(x: Int) = if (x >= 0) x else -x

call by val:  (x:Int)

call by name:   (y:=>Int)

2. blocks and lexical scope

def sqrt(x: Double) = {
　　def sqrtIter(guess: Double): Double =
　　　　if (isGoodEnough(guess)) guess
　　　　else sqrtIter(improve(guess))
　　def improve(guess: Double) =
　　　　(guess + x / guess) / 2
　　def isGoodEnough(guess: Double) =
　　　　abs(square(guess) - x) < 0.001
　　sqrtIter(1.0)

 

 

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