Implement terminating operation on (Boolean, A).

X.scala

case class X[A](ok: Boolean, value: A) { 
  def map[B](f: A => B): X[B] = 
    X(ok, f(a))

  def flatMap[B](f: A => X[B]) X[B] =
    f(value)
 
  def thenOr[B](f: A => X[B], otherwise: A => B) = 
   if (ok) then flatMap(f) else map(otherwise)
}

object XClient {
  val x = for {
    a <- X(true, 1)        // will continue no matter value of ok
    b <- X(false, "asf")   // will continue no matter value of ok
    c <- X(true, a).thenOr(_ => X(true, "something"), _ => "else")  // c will be something
    d <- X(false, a).thenOr(_ => X(true, "something"), _ => "else")  // d will be else
  } yield z
}