Auth.scala

  class Auths[F[_]](implicit I: Inject[Auth,F]) {
    def login(id: UserId, pwd: Password): FreeC[F,Option[User]] =
      lift(Login(id, pwd))
    def hasPermission(u: User, p: Permission): FreeC[F,Boolean] =
      lift(HasPermission(u, p))

    type AuthCoyo[A] = Coyoneda[F, A]
    type AuthFree[A] = Free[AuthCoyo, A]
    def point[A](a: ⇒ A): Free.FreeC[F, A] = Monad[AuthFree].point(a)
  }