Vending_3.fsx

// test
let consolePrinter = Printer(System.Console.Out.WriteLine)
let vm = VendingMachine(3, consolePrinter)
consolePrinter.Print(sprintf $"Current stock: {vm.GetStock()}")
// fsi:
// Current stock: 3

let custId1 = 1
let custId2 = 2

vm.BuyItem(custId1)
// fsi:
// Vend item to customer 1
// New stock: 2

vm.BuyItem(custId2)
// fsi:
// Vend item to customer 2
// New stock: 1

vm.BuyItem(custId1)
// fsi:
// Vend item to customer 1
// New stock: 0

vm.BuyItem(custId2)
// fsi:
// Request for customer 2 will be fulfilled after machine is restocked

vm.BuyItem(custId1)
// fsi:
// Request for customer 1 will be fulfilled after machine is restocked

vm.Restock(3)
// fsi:
// Restocking with 3
// Current stock: 3
// Vend item to customer 2
// New stock: 2
// Vend item to customer 2
// New stock: 1

vm.Restock(7)
// fsi:
// Restocking with 7
// Current stock: 8