definition.scala

import shapeless._

object definition {


  case class Property[A](a: A)
  case class Embed[A](a: A)
  case class Hidden[A](a: A)

  def Prop[X] = Property[X] _
  def Emb[X] = Embed[X] _
  def Hid[X] = Hidden[X] _

  trait Representation[A] {
    type Repr <: HList
    val repr: Repr

  }

  object Representation {
    type Aux[A, R] = Representation[A]{ type Repr = R }
    def apply[A, R <: HList](genA: Generic[A], r: R)(implicit typeAlignment: TypeAlignment[genA.Repr, R]): Aux[A, R] = new Representation[A] {
      type Repr = R
      val repr = r
    }
  }



  case class TypeAlignment[A, B]()

  object TypeAlignment {

    implicit def hnilTypeAlign2: TypeAlignment[HNil, HNil] = new TypeAlignment[HNil, HNil]()

    implicit def propertyRightAlign[A]: TypeAlignment[A, A => Property[A]] = new TypeAlignment[A, A => Property[A]]()
    implicit def embedRightAlign[A]: TypeAlignment[A, A =>  Embed[A]] = new TypeAlignment[A, A => Embed[A]]()
    implicit def hiddenRightAlign[A]: TypeAlignment[A, A =>  Hidden[A]] = new TypeAlignment[A, A => Hidden[A]]()

    implicit def hlistTypeAlign[A, B, TA <: HList, TB <: HList](implicit headAlignment: TypeAlignment[A, B], tailAlignment: TypeAlignment[TA, TB]): TypeAlignment[A :: TA, B :: TB] = new TypeAlignment[A :: TA, B :: TB]()

  }
}

demo.scala

import shapeless._

object demo {
  import definition._


  type ACL = String

  case class Address(city: String, street: String, zipcode: String)

  case class User(name: String, age: Option[Int], address: Address, acl : ACL)
  val userRepr = Prop[String] :: Prop[Option[Int]] :: Emb[Address] :: Hid[ACL] :: HNil
  val bogusRepr = Prop[String] :: Prop[Int] :: Emb[Address] :: Hid[ACL] :: HNil


  /*def makeUserRepr(implicit gen: Generic[User]) = {
    val genUser = Generic[User]
    Representation(genUser, userRepr)
  }*/

}