Unwrap.scala

object Unpack:
  import scala.quoted._
  import scala.compiletime._

  private def tupleType(s: String)(using q: Quotes): q.reflect.TypeRepr =
    import q.reflect._
    val typeParams =
      s.map{ c =>
        TypeRepr.of(using ConstantType(CharConstant(c)).asType)
      }.toList
    assert(typeParams.length > 0)
    assert(typeParams.length < 23)
    typeParams.length match
      case 1 => typeParams.head
      case l =>
        TypeRepr.typeConstructorOf(Class.forName(s"scala.Tuple$l"))
          .appliedTo(typeParams)

  private def unpackImpl[S <: Singleton & String: Type](using q: Quotes): Expr[Any] =
    import q.reflect._
    TypeRepr.of[S] match
      case ConstantType(StringConstant("")) =>
        '{EmptyTuple}
      case ConstantType(StringConstant(str)) =>
        tupleType(str).asType match
          case '[tpe] =>
            '{ Tuple.fromArray(${Expr(str.toArray)}).asInstanceOf[tpe] }

  transparent inline def unpack[T <: Singleton & String] =
    ${ unpackImpl[T] }