OO type class

tcoo.scala

//============== the OO version

  trait Eq[A] { // the type trait
    def sameAs(b:A) : Boolean   // so many name clashes with eq/equals etc
  }
  
  case class Student (name:String) extends Eq[Student] { // classic OO implementation
    override def sameAs(b:Student) = this.name == b.name
  }
  
    // someone actually using the Eq: A must be a subtype of Eq
  def member[A <: Eq[A]] (a:A, container:List[A]) = 
    container.exists(_.sameAs(a))

  member (Student("John"), List(Student("John")))