gistfile1.scala

import scalaz._
import Scalaz._
import scala.concurrent.Future
import scalaz.contrib.std.scalaFuture._ // typeclass instances for Scala Future
import scala.concurrent.ExecutionContext.Implicits.global // implicit execution context...you probably want a better one for real-world

type ErrorsOrT[M[+_], +A] = EitherT[M, NonEmptyList[String], A] // String could be your error type of choice

for {
  thing1 <- EitherT(Future.successful(1.right))
  thing2 <- Future.successful(2).liftM[ErrorsOrT]
} yield {
  thing1 + thing2
}


res7: scalaz.EitherT[scala.concurrent.Future,scalaz.NonEmptyList[String],Int] = scalaz.EitherTFunctions$$anon$11@45d1a86c

for {
  thing1 <- Future.successful("Kebab").liftM[ErrorsOrT]
  thing2 <-  EitherT(Future.successful(1.right))
} yield thing1 + thing2