Set proper artifact names.
package net.tz.spss
sealed trait SpssValue
sealed trait Missing extends SpssValue
abstract class Value[T] extends SpssValue {
def v: T
}
abstract class MissingValue[T] extends Value[T]
case class StringValue(v: String) extends Value[String]
case class DoubleValue(v: Double) extends Value[Double]
case object SystemMissing extends Missing
// ??? case class MissingString(v: String) extends MissingValue[String]
case class MissingDouble(v: Double) extends MissingValue[Double]