Scalaz Trampoline 7.0.2 on 2.10.2 fail...

gistfile1.txt

class CTree extends Specification{
  "map" should {
    "work with a tree without roots" in { //Works!
      val blah = CTree(1)
      val yo = blah map (_ + 1)

      yo.root must beEqualTo(2)
    }
    "work with nested trees" in { //Fails! java.lang.AbstractMethodError...
      val blah = CTree(1, Map(1 -> CTree(1)))
      val yo = blah map (_ + 1)

      (yo.root must beEqualTo(2)) and
        (yo.children(1).root must beEqualTo(2))
    }
  }
}

Tree.scala

case class CTree[@specialized(Double) Value](root: Value,
                               children: Map[Int, ComputedTree[Value]] = Map.empty[Int, CTree[Value]]){

  def map[A](f: Value => A): ComputedTree[A] = walk(this, f).run

  protected def walk[A](tree: CTree[Value], f: Value => A): Trampoline[CTree[A]] = tree match {
    case CTree(value, childs) if childs.isEmpty => done(CTree(f(value)))
    case CTree(value, childs)                   => step(childs.toList, f) map (CTree(f(value), _))
  }

  protected def step[A](trees: List[(Int, CTree[Value])],
                        f: Value => A,
                        acc: List[(Int, CTree[A])] = Nil): Trampoline[Map[Int, CTree[A]]] = trees match {
    case (id, head) :: tail => for {
      that <- suspend(walk(head, f))
      remainder <- suspend(step(tail, f, (id, that) :: acc))
    } yield remainder
    case Nil => done(acc.toMap)
  }
}

Maybe scalac bug. will be fixed in Scala2.11