typeclass code from NEScala talk

Typeclasses.scala

case class Person(
  name: String,
  age: Int)

case class Restaurant(
  name: String,
  brunch: Boolean)

// "ser" could just be "apply"

trait Serializable[T] {
  def ser(t: T): String
}

def serialize[T](t: T)
                (implicit s: Serializable[T]) =
  s.ser(t)

implicit object PersonIsSerializable
extends Serializable[Person] {
  def ser(p: Person) =
    "Person(" + p.name + "," + p.age + ")"
}

implicit object RestaurantIsSerializable
extends Serializable[Restaurant] {
  def ser(r: Restaurant) =
    "Restaurant(" + r.name + "," + r.brunch + ")"
}

println(serialize(Person("Seth", 40)))

implicit def ListIsSerializable[T : Serializable] =
  new Serializable[List[T]] {
    def ser(xs: List[T]) =
      xs.map(serialize(_))
        .mkString("List(", ",", ")") }

println(serialize(List(Person("Seth", 40),
                       Person("Kaarin", 43))))