Scala: Pattern matching when one of two items meets some condition

Question

I\'m often writing code that compares two objects and produces a value based on whether they are the same, or different, based on how they are different.

So I might writ

Answer 1

Since you already matched against (Some(x), Some(y)), you may match against (None, None) explicitly, and the remaining cases are (Some(x), None) and (None, Some(y)):

def decide [T](v1: Option[T], v2:Option[T]) = (v1, v2) match {
  case (Some (x), Some (y)) => "a"
  case (None, None)         => "c"
  case _                    => "b"
}

val ni : Option [Int] = None 
decide (ni, ni)            // c
decide (Some (4), Some(3)) // a
decide (ni, Some (3))      // b
decide (Some (4), ni)      // b