Using emojis as class names.

EmojiCode.swift

import Foundation

protocol JuiceContaining {
    var volume: Double { get }
    var juiceRatio: Double { get }
}

protocol DrinkProducing {
    var drinkVolume: Double { get }
}

extension DrinkProducing where Self: FruitContaining {
    var drinkVolume: Double {
        return fruit.volume * fruit.juiceRatio
    }
}

protocol FruitContaining {
    var fruit: JuiceContaining { get }
}

final class 🍉: NSObject, JuiceContaining {
    let volume: Double = 3
    let juiceRatio: Double = 0.33
}

final class 🍹<Fruit: NSObject & JuiceContaining>: FruitContaining, DrinkProducing {
    var fruit: JuiceContaining = Fruit()
}

let watermellonDrink = 🍹<🍉>()

print(watermellonDrink.drinkVolume) // => 0.99