TMonad.scala

trait TMonad[F[_, _]] {
  type State[S]
  type Compose[_, _, _]

  def pure[I, A](a: A)(implicit I: State[I]): F[I, A]
  def map[S, A, B](fa: F[S, A])(f: A => B): F[S, B]
  def ap[S1, S2, S, A, B](f: F[S1, A => B])(fa: F[S2, A])(implicit S: Compose[S1, S2, S]): F[S, B]
  def flatMap[S1, S2, S, A, B](fa: F[S1, A])(f: A => F[S2, B])(implicit S: Compose[S1, S2, S]): F[S, B]
}
object TMonad {
  type Aux[F[_, _], S[_], C[_, _, _]] = TMonad[F] {
    type State[A] = S[A]
    type Compose[A, B, C] = C[A, B, C]
  }
}

implicit def monad[F[_, _], I, S[_], C[_, _, _]]
(implicit F: TMonad.Aux[F, S, C], state: S[I], fixpoint: C[I, I, I]): Monad[F[I, ?]] = 
  new Monad[F[I, ?]] {
    def pure[A](a: A): F[I, A] = F.pure(a)
    def flatMap[A, B](fa: F[I, A])(f: A => F[I, B]): F[I, B] = F.flatMap(f)
  }
  
  
trait RMonad[F[_]] {
  type Constraint[A]

  def pure[A](a: A)(implicit A: F[A]): F[A]
  def map[A, B](fa: F[A])(f: A => B)(implicit B: F[B]): F[B]
  def ap[A, B](f: F[A => B])(fa: F[A])(implicit B: F[B]): F[B]
  def flatMap[A, B](fa: F[A])(f: A => F[B])(implicit B: F[B]): F[B]
}