scala 递归函数的几种写法

def fact(x:Int):Int= x match
    {
      case 1 => 1;
      case n => n*fact(n-1);
    }


lazy val fact: (Int, Int) => Int = (_: Int, _: Int) match {
      case (1, n) => n;
      case (n, m) => fact(n - 1, n * m);
    }


lazy val fact: (Int, Int) => Int =  {
      case (1, n) => n;
      case (n, m) => fact(n - 1, n * m);
    }