How to define logical operation `not` without conditionals and OOP dispatching

Bools.scala

object Bools extends App {
  class Bool(negated: () => Bool) {
    def not = negated()
  }

  val True: Bool = new Bool(() => False)
  val False: Bool = new Bool(() => True)

  assert(True == True)
  assert(False == False)
  assert(True != False)

  assert(True.not == False)
  assert(False.not == True)

  println("OK")
}