1  trait Heater extends OnOffDevice { 2     def on = println("heater.on") 3     def off = println("heater.off") 4  } 5  trait PotSensor extends SensorDevice { 6     def isCoffeePresent = false
7   }

1   object allDevices extends Heater with PotSensor

1  def trigger = { 2       if ( WarmerFuncImpl.thereIsCoffee(allDevices) ) 3  WarmerFuncImpl.warmerOn(allDevices) 4       else
5  WarmerFuncImpl.warmerOff(allDevices) 6   }                                               //> trigger: => scalaz.Id.Id[Unit] 7   //测试运行
8   trigger                                         //> heater.off

1  trait PotHasCoffee extends SensorDevice { 2     def isCoffeePresent = true
3   }

1   object allDevices extends Heater with PotHasCoffee

1 //测试运行
2   trigger                                         //> heater.on