error: forward reference extends over definition of value next

gistfile1.sbt

def iterationForCoin(stream: Stream[Int], coin: Int) = {
    val (lower, higher) = stream splitAt coin
    val next: Stream[Int] = lower #::: (higher zip next map { case (a, b) => a + b })
    next.toList
}
val coins = List(1, 2, 5, 10, 20, 50, 100, 200)
coins.foldLeft(1 #:: Stream.fill(200)(0))(iterationForCoin).last

Ok, solved it like this:

class IterationForCoin(stream: Stream[Int], coin: Int) {
    val (lower, higher) = stream splitAt coin
    val next: Stream[Int] = lower #::: (higher zip next map { case (a, b) => a + b })
}
val coins = List(1, 2, 5, 10, 20, 50, 100, 200)
val result = coins.foldLeft(1 #:: Stream.fill(200)(0)){
     (stream, coin) => new IterationForCoin(stream, coin).next
}.last