package practise6.exercises /* 练习 4 把: val add: (Int, Int) => Int = (a, b) => a + b 改成 _。 要求: println(add(10, 20)) 输出: 30 */ object Exercises4 { def main(args: Array[String]): Unit = { val add: (Int, Int) => Int = _ + _ println(add(10, 20)) } }