[scala] implementation hiding

All,

Am i being stupid or is it impossible in the code below to construct a natural way to hide the concrete case class?

Best wishes,

--greg

trait MBrace[C[X] <: MBrace[C,X],A] {
  def nest( a : A ) : C[A]
  def flatten[T <: C[C[A]]]( bsq : T ) : C[A]
}

// a monad that is a Seq
trait MBraceSeq[C[X] <: MBrace[C,X] with Seq[X],A] extends MBrace[C,A]

// one of the simplest witnesses of monad i can find
case class MSequitor[A]( a_ : A* ) extends Seq[A] with MBrace[MSequitor,A] {
  override def nest( a : A ) = new MSequitor[A]( a )
  override def flatten[T <: MSequitor[MSequitor[A]]]( bsq : T ) : MSequitor[A] = {
    (new MSequitor[A]( ) /: bsq)( {
      ( acc : MSequitor[A], e : MSequitor[A] ) => ( acc ++ e ).asInstanceOf[MSequitor[A]]     
    } )
  }
  override def length = a_.length
  override def elements = a_.elements
  override def apply( n : Int ) = a_.apply( n )
}

// a statement of the instance relation
class MBraceSequitor[A] extends MBraceSeq[MSequitor,A] {
  val empty : MSequitor[A] = new MSequitor[A]( )
  override def nest( a : A ) = empty.nest( a )
  override def flatten[T <: MSequitor[MSequitor[A]]]( bsq : T )
  : MSequitor[A] = empty.flatten( bsq )
}

--
L.G. Meredith
Managing Partner
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