Very naive and simple example of filtering out conflicting appointments based on availabilities for an appointment scheduler.

gistfile1.scala

  def getAvailabilities(date: Date, length: String): Seq[AvailableTime] = {
    val at = AvailableTime(None, new Date(System.currentTimeMillis()), "10", "30")
    val at2 = AvailableTime(None, new Date(System.currentTimeMillis()), "10", "45")
    val at3 = AvailableTime(None, new Date(System.currentTimeMillis()), "11", "15")
    val at4 = AvailableTime(None, new Date(System.currentTimeMillis()), "14", "30")
    val at5 = AvailableTime(None, new Date(System.currentTimeMillis()), "15", "45")
    val at6 = AvailableTime(None, new Date(System.currentTimeMillis()), "16", "15")
    val at7 = AvailableTime(None, new Date(System.currentTimeMillis()), "17", "30")
    val times = Seq(at, at2, at3, at4, at5, at6, at7)

    val appt = Appointment(None, new Date(), "11", "45", 60, "housecall", 1)
    val appt2 = Appointment(None, new Date(), "19", "00", 45, "housecall", 1)
    val appts = Some(Seq(appt, appt2))

    times.filter(time => isTimeAvailable(time, appts))
  }

  private def isTimeAvailable(availableTime: AvailableTime, maybeAppointments: Option[Seq[Appointment]]) = {
    maybeAppointments match {
      case Some(appointments) => {
        val conflict = appointments.exists(appt => isDateOverlap(appt.startDate, appt.endDate, availableTime.startDate, availableTime.endDate))
        !conflict
      }
      case None => true
    }
  }

  private def isDateOverlap(startDate1: DateTime, endDate1: DateTime, startDate2: DateTime, endDate2: DateTime) = {
    (startDate1 <= endDate2) && (startDate2 <= endDate1)
  }

Declared conflict as a val simply to make the code more readable.