ifElseM.scala

def ifElseM[F[_]: FlatMap, A](branches: (F[Boolean], F[A])*, els: F[A]): F[A] = {
  def loop(branches: List[(F[Boolean], F[A])]): F[A] =
    branches match {
      case (cond, conseq) :: tail => 
        cond.flatMap(if (_) conseq else loop(tail))

      case Nil => 
        els
    }

  loop(branches.toList)
}