A comparison of pattern matching and equivalent imperative solution

patternMatching.scala

// groups only holds lists of "good" things and "bad" things
val groups = Map('good -> List("beer", "bikes"), 'bad -> List("flat tires"))

// But we're interested in both "good" things and "not too bad" things
val known = (groups.get('good), groups.get('notTooBad)) match {
  case (Some(goodThings), Some(notTooBadThings)) => "i know about good and not-too-bad things"
  case (Some(goodThings), None) => "i know about good things only"
  case (_, None) => "i might know about good things but nothing else"
  case _ => "i may or may not know anything"
}

// Here's an imperative equivalent
var goodThings = null
var notTooBadThings = null
if (groups.containsKey('good))
  goodThings = groups('good)
if (groups.containsKey('notTooBad))
  notTooBadThings = groups('notTooBad)

val knownImperative =
  if (goodThings != null && notTooBadThings != null) "i know about good and not-too-bad things"
  else if (goodThings != null && notTooBadThings == null) "i know about good things only"
  else if (notTooBadThings == null) "i might know about good things but nothing else"
  else "i may or may not know anything"