函数的字面量语法

object base39 {
  def sum(x:Int,y:Int):Int={
    x+y
  }
  val a=1
  val sum1=(x:Int,y:Int) => {x+y}

  val sum2=(x:Int,y:Int) => x+y
  val sum3 :(Int,Int) =>Int = { _ + _ }
  val sum4=(_:Int)+(_:Int)

  def main(args: Array[String]): Unit = {
    val a=2
    val n=5
    println(s"$a+$n=${sum1(a,n)}")
    println(s"$a+$n=${sum2(a,n)}")
    println(s"$a+$n=${sum3(a,n)}")
    println(s"$a+$n=${sum4(a,n)}")
  }
}