class CreateShowCommand extends ShowCommand[TiyatroSeverShow] {
  protected implicit val jsonFormats = DefaultFormats
  implicit def datetimeFormatValidator(s: FieldDescriptor[String]) = new DateTimeStringValidations(s)

  val title: Field[String] = asType[String]("title").notBlank.minLength(3)
  val schedule: Field[String] = asType[String]("schedule").notBlank.minLength(8).checkDateFormat()
  val stages: Field[Seq[String]] = asType[Seq[String]]("stages").notEmpty("Empty stages are not allowed")
}

object ShowData extends CommandHandler {
  protected def handle: Handler = {
    case s: CreateShowCommand => add(
      TiyatroSeverShow(~s.title.value, Parsers.StringToDateTime(~s.schedule.value), idcounter.incrementAndGet(), ~s.stages.value)
    )
  }
}

case class TiyatroSeverShow(title: String, schedule: List[DateTime], id: Int, stages: Seq[String] = Seq(""),
                            finished: Boolean = false)

[info] Compiling 3 Scala sources to /home/sinan/dev/tiyatrosever/target/scala-2.11/classes...
[error] /home/sinan/dev/tiyatrosever/src/main/scala/com/yokyer/tiyatrosever/data/ShowData.scala:23: could not find implicit value for parameter z: scalaz.Monoid[Seq[String]]
[error]       TiyatroSeverShow(~s.title.value, Parsers.StringToDateTime(~s.schedule.value), idcounter.incrementAndGet(), ~s.stages.value)
[error]                                                                                                                  ^
[error] one error found
[error] (compile:compile) Compilation failed
[error] Total time: 2 s, completed Aug 21, 2014 12:41:53 PM