Given a sealed trait A and a case class B, force the case class to have as parameters all and only the known subclasses of A (at compile time with shapeless)

CaseClassLink.scala

import shapeless._

sealed trait A
case object A1 extends A 
case object A2 extends A
case object A3 extends A
case class B(
  A1: String,
  A2: String,
  A3: String
)

val b = B("a", "b", "c")

class CaseClassLink[A, B] {
  def am[V <: HList, K <: HList, L <: HList, H <: HList, C <: Coproduct](b: B)(implicit
    bGen: LabelledGeneric.Aux[B, H],
    values: shapeless.ops.record.Values.Aux[H, V],
    kGen: LabelledGeneric.Aux[A, C],
    keys: ops.union.Keys.Aux[C, K],
    zip: ops.hlist.ZipWithKeys.Aux[K, V, L],
    b2Gen: LabelledGeneric.Aux[B, L]
  ): B = {
    val k: K = keys()
    val v: V = values(bGen.to(b))
    val l: L = v.zipWithKeys(k)
    b2Gen.from(l)
  }
}
val x = (new CaseClassLink[A, B]).am(b)

println(x)