Scala<计算代码运行时间>

object Demo {
  def time[R](block: => R): R = {
    val start = System.nanoTime()
    val result = block // call-by-name
    val end = System.nanoTime()
    println("\n\n--------------------------------")
    println("past:[" + (end - start) + "ns]")
    println("--------------------------------")
    result
  }

  def main(args: Array[String]): Unit = {
    time {1 to 1000 by 1 toList}
  }
}