fp-ddd chapter 4

Domain Modeling Made Functional - Chapter 4

Understand F# types

type CheckNumber = CheckNumber of int
type CardNumber = CardNumber of string

type CardType =
  Visa | Mastercard

type CreditCardInfo = {
  CardType: CardType
  CardNumber: CardNumber
}

// -------
type PaymentMethod =
  | Cash
  | Check of CheckNumber
  | Card of CreditCardInfo

type PaymentAmount = PaymentAmount of decimal
type Currency = EUR | USD

type Payment = {
  Amount: PaymentAmount
  Currency: Currency
  Method: PaymentMethod
}