在phadej的Haskell中给出以下Phantom Type示例：
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
newtype Distance a = Distance Double
deriving (Num, Show)
data Kilometer
data Mile
marathonDistance :: Distance Kilometer
marathonDistance = Distance 42.195
distanceKmToMiles :: Distance Kilometer -> Distance Mile
distanceKmToMiles (Distance km) = Distance (0.621371 * km)
marathonDistanceInMiles :: Distance Mile
marathonDistanceInMiles = distanceKmToMiles marathonDistance
我试图将其转换为Scala：
case class Distance[A](x: Double) extends AnyVal
case object Kilometer
case object Mile
def marathonDistance: Distance[Kilometer.type] = Distance[Kilometer.type](42.195)
def distanceKmToMiles(kilos: Distance[Kilometer.type]): Distance[Mile.type] =
Distance[Mile.type](kilos.x * 0.621371)
def marathonDistanceInMiles: Distance[Mile.type] = distanceKmToMiles( marathonDistance )
假设这个Phantom Type实现在Scala中有效，那么Distance的这种用法是否会导致分配，即使用堆而不是堆栈？
如果它会分配，原因是什么？