Can I store an intermediate result in an Scala case match?

Question

Say I have this:

def expensiveTest(t: String): Option[Int] = {...}
// myList: List[String]
myList.collectFirst {
  case x if expensiveTest(x).isDefined => expensiveTest(x).get
}

Something like this works, but... I have to call expensiveTest() twice. Is there a way to save the result of the guard's call to expensiveTest to use on the right side of the =>?

Answer 1

Switching the List to a lazy Stream and using a map/head could be an alternative:

myList.toStream.flatMap { case x => expensiveTest(x) }.head