scala学习笔记：高阶函数

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scala> def power(y:Double)=(x:Double)=>Math.pow(x,y)warning: there were 1 deprecation warnings; re-run with -deprecation for detailspower: (y: Double)Double => Doublescala> val square=power(2)square: Double => Double = <function1>scala> val squareRoot=power(0.5)squareRoot: Double => Double = <function1>scala> square(10)res0: Double = 100.0scala> squareRoot(100)res1: Double = 10.0

也可以定义成：

scala> def power = (x:Double)=> ((y:Double) => math.pow(x, y))power: Double => Double => Doublescala> power(4)(3)res8: Double = 64.0

也可以写成：

scala> :paste// Entering paste mode (ctrl-D to finish)def power(x:Double,y:Double) = math.pow(x, y)def square=power(_:Double,2)def squareroot(x:Double)=power(x,0.5)square(3)squareroot(3)// Exiting paste mode, now interpreting.power: (x: Double, y: Double)Doublesquare: Double => Doublesquareroot: (x: Double)Doubleres8: Double = 1.7320508075688772

柯里化之后：

def power(x:Double)(y:Double) = math.pow(x, y)def square=power(_:Double)(2)square(3)def squareroot(x:Double)=power(x)(0.5)squareroot(3)

power: (x: Double)(y: Double)Doublesquare: Double => Doublesquareroot: (x: Double)Doubleres7: Double = 1.7320508075688772

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