trait Bonus {
        def apply(baseValue: float)(value: float) -> float
        def order: int
    }

    class PercentBonus(value: Int) extends Bonus {
        @override
        def apply(baseValue: float) -> baseValue * (1 + value / 100)
        def order = 10
    }

    def addBonus(bonus: Bonus) = bonuses.add(bonus)

    def getValue = bonuses.orderBy(_.order).fold(baseValue, (value, bonus) -> bonus.apply(value))