How to type a tuple of any length but only having options in scala 3

Question

How could I have something like

var tuple : (Option[Any]) | (Option[Any], Option[Any]) | (Option[Any], Option[Any], Option[Any]) | (Option[Any], Option[Any], Option[Any], Option[Any])  

But more elegantly?

Answer 1

You can do something like this in scala3.0:

scala> type OptTuple[T <: Tuple] = T match
     |   case Option[_] *: t => OptTuple[t]
     |   case EmptyTuple => DummyImplicit
     |

scala> case class MyTuple[T <: Tuple : OptTuple](tuple: T)
// defined case class MyTuple

scala> val t1 = MyTuple((Option(1), Option("a"), Option(3.0)))
val t1: MyTuple[(Option[Int], Option[String], Option[Double])] = MyTuple((Some(1),Some(a),Some(3.0)))

scala> val t2 = MyTuple((Option(1), Option("a"), 3.0))
-- Error: ----------------------------------------------------------------------
1 |val t2 = MyTuple((Option(1), Option("a"), 3.0))
  |                ^
  |     Match type reduction failed since selector  Double *: EmptyTuple.type
  |     matches none of the cases
  |
  |         case Option[_] *: t => OptTuple[t]
  |         case EmptyTuple => DummyImplicit
1 error found