Span.scala

type SpanF[A, C] <: Tuple = (A, C) match
  case ((as, bs), (a, b)) => (as *: a, bs *: b)

type Span[A <: Tuple] = Fold[A, (EmptyTuple, EmptyTuple), SpanF]

def span[T <: Tuple](t: Tuple): Option[Span[T]] =
  def go[TT <: Tuple, A <: Tuple, B <: Tuple](remaining: TT, as: A, bs: B): Option[(A, B)] =
    remaining match
      case EmptyTuple => Some((as, bs))
      case (a, b) *: tt => go(tt, a *: as, b *: bs).asInstanceOf[Option[(A, B)]]
      case s => None

  go(t, EmptyTuple, EmptyTuple).asInstanceOf[Option[Span[T]]]


val input: ((Int, String), (Boolean, Double), (List[Int], List[String])) = ???
val output: Option[((Int, Boolean, List[Int]), (String, Double, List[String]))] = span(input)