2 level monad transformer

gistfile1.scala

import scalaz._
import Scalaz._

object console extends App {
  
  type ListTOption[A] = ListT[Option, A]

  val v1: Option[List[\/[String, Int]]] = 1.right[String].point[List].point[Option]
  val v2: Option[List[\/[String, Int]]] = 2.right[String].point[List].point[Option]

  val t1 = EitherT[ListTOption, String, Int](ListT(v1))
  val t2 = EitherT[ListTOption, String, Int](ListT(v2))

  val rt = for {
    v1 <- t1
    v2 <- t2
  } yield v1 + v2

  val res = rt.run.run

  println(s"res: ${res}")
}