universal.scala

// [info] Running p.Run
// List(Fish(Bob, Esq.,12), Kitty(Thor, Esq.,java.awt.Color[r=255,g=200,b=0]))

package misc

import java.awt.Color

trait Pet[A] {
  def name(a: A): String
  def renamed(a: A, newName: String): A
}
case class Fish(name: String, age: Int)
case class Kitty(name: String, color: Color)

object Fish {
  implicit object FishPet extends Pet[Fish] {
    def name(a: Fish) = a.name
    def renamed(a: Fish, newName: String) = a.copy(name = newName)
  }
}
object Kitty {
  implicit object KittyPet extends Pet[Kitty] {
    def name(a: Kitty) = a.name
    def renamed(a: Kitty, newName: String) = a.copy(name = newName)
  }
}

trait Item[TC[x]] {
  type Elm
  def elm: Elm
  def concept: TC[Elm]
}

object Item {
  implicit def liftElm[TC[x], A: TC](x: A): Item[TC] = new Item[TC] {
    type Elm = A
    def elm = x
    def concept = implicitly[TC[Elm]]
  }
}

object Run {
  def esquire(pet: Item[Pet]): pet.Elm = {
    pet.concept.renamed(pet.elm, pet.concept.name(pet.elm) + ", Esq.")
  }

  def main(args: Array[String]): Unit = {
    val bob     = Fish("Bob", 12)
    val thor    = Kitty("Thor", Color.ORANGE)
    val pets    = List[Item[Pet]](bob, thor)
    val renamed = pets map (x => esquire(x))

    println(renamed)
  }
}