Scala - Custom ordering

CustomOrdering.scala

case class Employee(id: Int, firstName: String, lastName: String)

object Employee {
  // Note that because `Ordering[A]` is not contravariant, the declaration
  // must be type-parametrized in the event that you want the implicit
  // ordering to apply to subclasses of `Employee`.
  implicit def orderingByName[A <: Employee]: Ordering[A] =
    Ordering.by(e => (e.lastName, e.firstName))

  val orderingById: Ordering[Employee] = Ordering.by(e => e.id)
}

http://stackoverflow.com/questions/19345030/easy-idiomatic-way-to-define-ordering-for-a-simple-case-class
http://stackoverflow.com/questions/14695833/scala-idiom-for-ordering-by-multiple-criteria
http://reactive.xploregroup.be/blog/8/Sorting-on-multiple-fields-and-Tuples

Pending review:

final class CompositeOrdering[T](val ord1: Ordering[T], val ord2: Ordering[T]) extends Ordering[T] {
  def compare(x: T, y: T) = {
    val comp = ord1.compare(x, y)
    if (comp != 0) comp else ord2.compare(x, y)
  }
}
object CompositeOrdering {
  def apply[T](orderings: Ordering[T] *) = orderings reduceLeft (_ orElse _)
}
trait OrderingOps {
   implicit class OrderingOps[T](ord: Ordering[T]) extends AnyVal {
    def orElse(ord2: Ordering[T]) = new CompositeOrdering[T](ord, ord2)
  }    
}