You can also implement a contains method with foldLeft, it's pretty awesome. I just love foldLeft algorithms.
For example:
object ContainsWithFoldLeft extends App {
val list = (0 to 10).toList
println(contains(list, 10)) //true
println(contains(list, 11)) //false
def contains[A](list: List[A], item: A): Boolean = {
list.foldLeft(false)((r, c) => c.equals(item) || r)
}
}