import scala.collection.mutable._ trait BugTrack { trait B[+T] val cache : HashMap[A[_], B[_]] = HashMap.empty def A[T](f: Int => B[T]): A[T] = new A[T]{def apply(in: Int) = f(in)} abstract class A[+T] extends (Int => B[T]) { def giveMeSame = this } def amethod[T](p: =>A[T]): A[T] = A(in => cache.get(p) match { case Some(res) => res case None => p(in) }).giveMeSame.asInstanceOf[A[T]] }