深圳scala-meetup-20180902（1）- Monadic 程式設計風格
阿新 • • 發佈：2018-12-10
type FoodName = String
type Quantity = Int
type FoodStore = KVStore[String,Int]
def addFood(food: FoodName, qty: Quantity )(implicit fs: FoodStore): Future[Unit] = for {
current <- fs.read(food)
newQty = current.map(cq => cq + qty ).getOrElse(qty)
_ <- fs.update(food, newQty)
}