Note that you don’t have to specify a return type for Scala to return something other than Unit. For example, your getPositions method could be written as such:

def getPositions(moves : Array[String]) = {
moves.map(move => Integer.parseInt(move))
}

Scala will infer the return type of methods that do not contain an explicit return keyword. What you likely ran into was that if the method doesn’t have a ‘=’ before the method body then its return type will be Unit. Otherwise the return value is the last expression in the method body.

Also, I’d write the isWinner function like so, using exists:

def isWinner(positions : Array[Int]) = winningCombos.exists( combo => combo.isMatch(positions))

or even

def isWinner(positions : Seq[Int]) = winningCombos.exists(_.isMatch(positions))

Cheers,
James