Nomikai.swift

protocol Drinkable {
}

struct 🍶: Drinkable {}
struct 🍺: Drinkable {}
struct 🍸: Drinkable {}

struct Person {
}

extension Person: ObserverType {
    public func on(_: Event<Drinkable>) {
        print("happy!")
    }
}

class Nomikai {
    private let publisher = PublishSubject<Drinkable>()
    private let disposeBag = DisposeBag()
    
    func join(_ person: Person) {
        publisher
            .subscribe(person)
            .disposed(by: disposeBag)
    }
    
    func serve() {
        publisher.onNext(🍶())
        publisher.onNext(🍺())
        publisher.onNext(🍸())
    }
}

func startNomikai() {
    let nomikai = Nomikai()
    let person = Person()
    nomikai.join(person)
    while true {
        nomikai.serve()
    }
}