gistfile1.scala

import scala.collection.mutable._

class Foo {

}

object Foo {
  trait Transform[-A >: B, B, +R[_] <: Set[_]] {
    def apply(a: A) : R[B]
  }
  
  class Person(val name: String)
  case class Student(override val name: String, val matrNum: Int) extends Person(name) {
    def rev = Student(name, matrNum.toString().reverse.toInt)
  }
  
  class PersToStud extends Transform[Person,Student,HashSet] {
    def apply(a:Person):HashSet[Student] = a match {
      case x:Student => HashSet(x.rev)
      case _ => HashSet()
    }
  }
  def main(args:Array[String]) {
    var pts: Transform[Student,Student,Set] = new PersToStud
    println(pts(new Student("julia",1234)))
  }
  
}