memo
scala> def unless(exp:Boolean)(code: => Unit) = if (!exp) code unless: (exp: Boolean)(code: => Unit)Unit scala> val x: Int = 20 x: Int = 20 scala> :paste // Entering paste mode (ctrl-D to finish) unless(x < 19) { println("小さい") } // Exiting paste mode, now interpreting. 小さい scala>