ঢ়ଶΛྻڍܕͰදݱ͢Δ sealed trait State object State { case object Requested extends State case object Paid extends State case object Failed extends State } ※࣮ࡍ͏ͪΐͬͱ͍Ζ͍Ζ͋Γ·͢
ίʔυྫ case class EntityKey[ID]( val repr: String ) extends AnyVal abstract class Entity[K, +V]( val id: EntityKey[K], val value: V )(implicit ev: V <:< K)
ίʔυྫ case class EntityKey[ID]( val repr: String ) extends AnyVal abstract class Entity[K, +V]( val id: EntityKey[K], val value: V )(implicit ev: V <:< K) phantom type
ίʔυྫ case class EntityKey[ID]( val repr: String ) extends AnyVal abstract class Entity[K, +V]( val id: EntityKey[K], val value: V )(implicit ev: V <:< K) ܕΛڞมʹ
ίʔυྫ case class EntityKey[ID]( val repr: String ) extends AnyVal abstract class Entity[K, +V]( val id: EntityKey[K], val value: V )(implicit ev: V <:< K) ͷܕ͕IDͷܕͷαϒΫϥεͰ͋Δ ܕύϥϝʔλ੍