Compile time HList for types

gistfile1.txt

// This was my proof of concept sketch for doing matcher factories with an
// compile-time HList for type constructors instead of code-generated MatcherFactoryN's.
// I just stored regular types here, but I figured it would be straightforward to
// make those type constructors. I never tried doing the implicit recursive unrolling
// that would be required to actually use something like this in ScalaTest, but that
// would be fun to try as an intellectual exercise. For ScalaTest I decided that even
// if I could get that working, it would end up being too "clever" for ScalaTest, so
// I opted for the MatcherFactoryN's that I felt would be simpler for users to understand.

sealed trait MatcherFactory

final case class MFNode[+H, +T <: MatcherFactory]() extends MatcherFactory {
  def prepend[J]: MFNode[J, MFNode[H, T]] = MFNode[J, MFNode[H, T]]()
  override def toString = "MFNode"
}

trait MFNil extends MatcherFactory { // I don't think I need this trait
  def prepend[H]: MFNode[H, MFNil] = MFNode[H, MFNil]()
  override def toString = "MFNil"
}

case object MFNil extends MFNil

type A = Int
type B = String
type C = Object

MFNil.prepend[A].prepend[B].prepend[C]

If you paste this into a scala REPL you'll see:

scala> MFNil.prepend[A].prepend[B].prepend[C]
res0: MFNode[C,MFNode[B,MFNode[A,MFNil]]] = MFNode