A simpler way to returning the "current" type in Scala.

/** This is in reference to @tploecat's blog http://tpolecat.github.io/2015/04/29/f-bounds.html
 *  where he compares F-bounded polymorphism and type classes for implementing "MyType".
 * 
 *  Curiously, the in my mind obvious solution is missing: Use abstract types.
 * 
 *  A lot of this material, including an argument against F-bounded for the use-case
 *  is discussed in:
 * 
 *  Kim B. Bruce, Martin Odersky, Philip Wadler:
 *  A Statically Safe Alternative to Virtual Types. ECOOP 1998: 523-549
 */
trait Pet {
  type This <: Pet
  def name: String
  def renamed(newName: String): This
}

case class Fish(name: String, age: Int) extends Pet {
  type This = Fish
  def renamed(newName: String): Fish = copy(name = newName)
}

case class Kitty(name: String, age: Int) extends Pet {
  type This = Kitty
  def renamed(newName: String): Kitty = copy(name = newName)
}

object Test {
  def esquire[A <: Pet](a: A): a.This = a.renamed(a.name + ", Esq.")
  val f: Fish = esquire(new Fish("bob", 22))
}