import shapeless._
import shapeless.ops.hlist._
import shapeless.ops.record._

case class Foo(i: Int, b: String)

object Main {

  def f[T, R <: HList, L <: HList]
  (g: LabelledGeneric.Aux[T, R])
  (implicit
   ks: Keys.Aux[R, L],
   tta: ToTraversable.Aux[L, Seq, Symbol],
   lub: LUBConstraint[L, Symbol]
  ) = {
    ks.apply.to[Seq].map(_.name)
  }

  def main(args: Array[String]): Unit = {
    val g = LabelledGeneric[Foo]
    println(f(g))
  }
}