Scala实现a~b f（x）函数

类似于数学中，有个f(x),然后求指定a—b时f(x)的值
f(x)可以自定义

上代码

package com.ysk/**  * Created by Y.S.K on 2017/8/31 in spark02.  * 求a---b f(x)  */object sumfunc extends App {  def sum(f: Int => Int)(a: Int)(b: Int): Int = {    @annotation.tailrec    def loop(n: Int, acc: Int): Int = {      if (n > b) {        println(s"n=${n},acc=${acc}")        acc      } else {        println(s"n=${n},acc=${acc}")        loop(n + 1, acc + f(n))      }    }    loop(a, 0)  }  sum(x => x)(1)(5)  sum(x => x * x)(1)(5)  sum(x => x * x * x)(1)(5)  val sumSquare = sum(x => x * x * x) _  sumSquare(1)(5)}

输出结果

n=1,acc=0
n=2,acc=1
n=3,acc=3
n=4,acc=6
n=5,acc=10
n=6,acc=15
n=1,acc=0
n=2,acc=1
n=3,acc=5
n=4,acc=14
n=5,acc=30
n=6,acc=55
n=1,acc=0
n=2,acc=1
n=3,acc=9
n=4,acc=36
n=5,acc=100
n=6,acc=225
n=1,acc=0
n=2,acc=1
n=3,acc=9
n=4,acc=36
n=5,acc=100
n=6,acc=225