Scala：操作のリストを無料のモナドに構成するにはどうすればよいですか？

私は私が望むことをする無料のモナドを持っています：

type FreeOperation[F] = Free[Operation, F]

sealed trait Operation[O]
case object IdentityOperation extends Operation[GraphTraversal[_, _]]
case class LabelOperation(label: String) extends Operation[GraphTraversal[_, Vertex]]
case class HasOperation(has: String, within: List[_]) extends Operation[GraphTraversal[_, Vertex]]
case class InOperation(in: String) extends Operation[GraphTraversal[_, Vertex]]
case class OutOperation(out: String) extends Operation[GraphTraversal[_, Vertex]]
case class InEdgeOperation(inEdge: String) extends Operation[GraphTraversal[_, Edge]]
case class OutEdgeOperation(outEdge: String) extends Operation[GraphTraversal[_, Edge]]
case class InVertexOperation(inVertex: String) extends Operation[GraphTraversal[_, Vertex]]
case class OutVertexOperation(outVertex: String) extends Operation[GraphTraversal[_, Vertex]]
case class AsOperation(as: String) extends Operation[GraphTraversal[_, _]]
case class SelectOperation(select: List[String]) extends Operation[GraphTraversal[_, _]]

object Operation {
  def identity: FreeOperation[GraphTraversal[_, _]] = Free.liftF(IdentityOperation)
  def label(v: String): FreeOperation[GraphTraversal[_, Vertex]] = Free.liftF(LabelOperation(v))
  def has(h: String, w: List[_]): FreeOperation[GraphTraversal[_, Vertex]] = Free.liftF(HasOperation(h, w))
  def in(i: String): FreeOperation[GraphTraversal[_, Vertex]] = Free.liftF(InOperation(i))
  def out(o: String): FreeOperation[GraphTraversal[_, Vertex]] = Free.liftF(OutOperation(o))
  def inEdge(ie: String): FreeOperation[GraphTraversal[_, Edge]] = Free.liftF(InEdgeOperation(ie))
  def outEdge(oe: String): FreeOperation[GraphTraversal[_, Edge]] = Free.liftF(OutEdgeOperation(oe))
  def inVertex(iv: String): FreeOperation[GraphTraversal[_, Vertex]] = Free.liftF(InVertexOperation(iv))
  def outVertex(ov: String): FreeOperation[GraphTraversal[_, Vertex]] = Free.liftF(OutVertexOperation(ov))
  def as(a: String): FreeOperation[GraphTraversal[_, _]] = Free.liftF(AsOperation(a))
  def select(s: List[String]): FreeOperation[GraphTraversal[_, _]] = Free.liftF(SelectOperation(s))
}

def operationInterpreter(traversal: GraphTraversal[_, _]): (Operation ~> Id) =
  new (Operation ~> Id) {
    def apply[A](input: Operation[A]): Id[A] =
      input match {
        case IdentityOperation => traversal.asInstanceOf[A]
        case LabelOperation(label) => traversal.hasLabel(label).asInstanceOf[A]
        case HasOperation(has, within) => traversal.has(has, P.within(within: _*)).asInstanceOf[A]
        case InOperation(in) => traversal.in(in).asInstanceOf[A]
        case OutOperation(out) => traversal.out(out).asInstanceOf[A]
        case InEdgeOperation(inEdge) => traversal.inE(inEdge).asInstanceOf[A]
        case OutEdgeOperation(outEdge) => traversal.outE(outEdge).asInstanceOf[A]
        case InVertexOperation(inVertex) => traversal.inV().asInstanceOf[A]
        case OutVertexOperation(outVertex) => traversal.outV().asInstanceOf[A]
        case AsOperation(as) => traversal.as(as).asInstanceOf[A]
        case SelectOperation(select) => {
          if (select.isEmpty) {
            traversal
          } else if (select.size == 1) {
            traversal.select[Any](select.head).asInstanceOf[A]
          } else {
            traversal.select[Any](select.head, select.tail.head, select.tail.tail: _*)
          }
        }
      }
  }

私はそれをそのように呼んでプログラムを作成することができます：

def selectQuery: Free[Operation, GraphTraversal[_, _]] =
  for {
    _ <- label("person")
    _ <- as("people")
    _ <- outEdge("created")
    _ <- has("weight", List(1.0))
    _ <- inVertex("software")
    _ <- as("software")
    x <- select(List("people", "software"))
  } yield x

val traversal = graph.traversal.V()
val result = selectQuery.foldMap(operationInterpreter(traversal))

涼しい！しかし、ここに問題があります：

私が持っているList[Operation]私はそれをどのように行うのか...私はこのモナドの構造に変換したいということを？

def composeQuery(query: List[Operation[_]]): FreeOperation[GraphTraversal[_, _]] = {
  query.foldLeft(???) (??????)
}

私の翻訳する正しい方法は何であるListのをOperations、私は私の通訳を渡すことができるという自由モナドには？