OptionT usage example.scala

import scala.concurrent.Future
import scalaz._            
import Scalaz._
import scala.concurrent.ExecutionContext.Implicits.global
  
 val fa = OptionT( Future { 1.some } )//Returns  an OptionT[Future,Int]
 val fb = OptionT( Future { 2.some } )
  //we don't need to nest for comprehensions since the OptionT unwraps the Option
  // automatically in addition to whatever monad it's abstracting over
  for {
   a <- fa
   b <- fb
 } yield (a + b)