Domain Modeling Made Functional

The Complete Pipeline

We’ve made a first pass at the design, so let’s review what we have so far. First, we’ll write down the types for the public API. We’ll typically put them all in one file, such as DomainApi.fs or something similar.

Here are the inputs:

// ----------------------
// Input data
// ----------------------

type UnvalidatedOrder = {
  OrderId : string
  CustomerInfo : UnvalidatedCustomer
  ShippingAddress : UnvalidatedAddress
  }
and UnvalidatedCustomer = {
  Name : string
  Email : string
  }
and UnvalidatedAddress = ...

// ----------------------
// Input Command
// ----------------------

type Command<'data> = {
  Data : 'data
  Timestamp: DateTime
  UserId: string
  // etc