Is there a way to avoid this kind of name collision?

existential_name_collision.scala

def newExistential[S]
    (producer: Inputs => S, consumer: S => Output)
    : Existential = {
  type SS = S
  val producer_ = producer
  val consumer_ = consumer
  new Existential {
    type S = SS
    def producer(is: Inputs) = producer_(is)
    def consumer(s: S) = consumer_(s)
  }
}