ordering.scala

trait Ordered[A] {
	  def compare(that: A): Int
	  def <  (that: A): Boolean = (this compare that) <  0
	  def >  (that: A): Boolean = (this compare that) >  0
	  def <= (that: A): Boolean = (this compare that) <= 0
	  def >= (that: A): Boolean = (this compare that) >= 0
	}
}

class Person(val name: String) extends Ordered[Person] {
  def compare (that: Person) = this.name.compare(that.name)
}

val tom = new Person("Tom")
val sue = new Person("Sue")
val thomas = new Person("Tom")

tom > sue     //true
thomas < tom  //false
tom >= thomas //true