MonadTransExample.scala

import scalaz._
import Scalaz._
import IndexedStateT._

type ParserM[S, A] = EitherT[({ type l[a] = StateT[Trampoline, S, a]})#l, String, A]

def getVerbose[S]: ParserM[S, S] = { 
    //https://github.com/scalaz/scalaz/blob/series/7.3.x/core/src/main/scala/scalaz/MonadState.scala
    val monadState = stateTMonadState[S, Trampoline]
    val state: StateT[Trampoline, S, S] = monadState.get
    //use liftM on StateT finding the implicit MonadTrans[EitherT] instance
    state.liftM[({ type l[a[_], b] = EitherT[a, String, b]})#l]
  }