channingwalton

 // ------------------------------------------------------
 // Combined List/Option/Either
 // ------------------------------------------------------
object MonadTransformers extends App {
  import scalaz._, Scalaz._
  import EitherT._

  type OptionTList[α] = ({ type λ[α] = OptionT[List, α] })#λ[α]

  val c1: EitherT[OptionTList, String, String] = eitherT[OptionTList, String, String](OptionT[List, \/[String, String]](List(some(\/-("c1a")), some(\/-("c1b")))))

channingwalton

object MonadWriterExample extends App {
  import scalaz._
  import Scalaz._

  implicit val monadWriter = EitherT.listenableMonadWriter[Writer, String, String]

  case class Person(firstName: String, age: Int, car: Option[String])

  def notEmpty(s: String) = Option(s).filter(x ⇒ !x.isEmpty && !x.forall(_.isWhitespace)) match {
    case Some(r) ⇒ monadWriter.right[String](r)