Yes, this an abuse of match. You've basically just written a big if-else-if block, but in a more awkward form. What's wrong with if-statements?
I think it's much cleaner to just write this:
def countChange(money: Int, coins: List[Int]): Int = {
if(money == 0) 1
else if (money < 0) 0
else if (coins.isEmpty) 0
else countChange(money, coins.tail) + countChange(money - coins.head, coins)
}
If you want to stick with a match
, you can move more of the checking into the match itself, so that it's actually doing something:
def countChange(money: Int, coins: List[Int]): Int = {
(money, coins) match {
case (0, _) => 1
case _ if (money < 0) => 0
case (_, Nil) => 0
case (_, coinsHead :: coinsTail) => countChange(money, coinsTail) + countChange(money - coinsHead, coins)
}
}