Customer_1.fsx

[<AutoOpen>]
module Customer =

    type internal CustomerMessage =
        | Order
        | Done

    type HungryCustomer (vendingMachine : VendingMachine, id : int, output : Printer) = 
        let agent = MailboxProcessor<CustomerMessage>.Start(fun inbox ->
            let rec orderLoop () = async {
                let! msg = inbox.Receive()
                match msg with
                | Order -> 
                    output.Print (sprintf $"Customer {id} is still hungry and orders another")
                    vendingMachine.BuyItem id
                    return! orderLoop ()
                | Done -> 
                    output.Print (sprintf $"Customer {id} is getting full, so stops ordering")
                    return ()
            }
            orderLoop() )
        
        member _.Order() = agent.Post Order
        member _.Done() = agent.Post Done