reduceRightOption
trait Collection[A] {
def reduceRightOption[B :> A](f: (A, B) => B): Option[B]
}
reduceRightOption
applies the binary operator op
to each element, going from right to left, and the previous op
result.
The first time op
is applied it’s fed with the last two elements.
The final result is wrapped with Some
.
On empty collections this function returns None
.