shapeless_long_example.scala

import shapeless._
import shapeless.ops.hlist

object mapper extends Poly1 {
  implicit def caseOpt[T] = at[Option[T]](_ => Option.empty[T])
}

def foo[S, SRep <: HList, O <: HList](s: S)(implicit
  labelledGeneric: Generic.Aux[S, SRep],
  map: hlist.Mapper.Aux[mapper.type, SRep, O],
  i1: Generic.Aux[S, O]
) = {
  i1.from(
    labelledGeneric.to(s).map(mapper)
  )
}

case class Qai(a: Option[String], b: Option[Int])

println {
  foo(Qai(Some("asdf"), Some(1))) //Qai(None, None)
}

case class Bar(a: Int, b: Option[Int])

// foo(Bar(1, None)) //Will Not compile