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sealed trait Option {}
case class Choice(a: Option, b: Option) extends Option;
case class Some(x: Boolean) extends Option;
case object None extends Option;
object test {
// drop any case and it will report an error
// note that booleans are taken into account
def f(opt: Option) = opt match {
case Choice(None, None) => 1;
case Choice(None, Some(_)) => 1;
case Choice(None, Choice(_, _)) => 1;
case Choice(Some(true), None) => 1;
case Choice(Some(false), None) => 1;
case Choice(Some(_), Some(_)) => 1;
case Choice(Some(_), Choice(_, _)) => 1;
case Choice(Choice(_, _), None) => 1;
case Choice(Choice(_, _), Some(_)) => 1;
case Choice(Choice(_, _), Choice(_, _)) => 1;
case Some(b) => 4;
case None => 5;
}
}
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