Quill: Tail recursive liftQuery macro

TupleQuery.scala

trait TupleQuery {
  this: io.getquill.context.Context[_, _] =>

  def liftTuples[T1: Encoder, T2: Encoder](l: List[(T1, T2)]): Quoted[Query[(T1, T2)]] =
    liftTuples(l, (t: (T1, T2)) => infix"(${lift(t._1)}, ${lift(t._2)})", null)

  private def liftTuples[T, U](l: List[T], f: T => Quoted[Any], acc: Quoted[Query[U]]): Quoted[Query[U]] = {
    l match {
      case Nil                         => infix"".as[Query[U]]
      case head :: Nil                 => infix"${f(head)}, $acc".as[Query[U]]
      case head :: tail if acc == null => liftTuples(tail, f, infix"${f(head)}".as[Query[U]])
      case head :: tail                => liftTuples(tail, f, infix"${f(head)}, $acc".as[Query[U]])
    }
  }
}