Blog.GuestList.Lens.Model.fs

open FPrimitive

type Guest =
  private { Name : string } with
    static member create name = result {
      let! name = specModel id name { 
        notNullOrWhiteSpace "guest name should not be blank"
        alphabetical "guest name should only contain alphabetical characters" }
      return { Name = name } }

type GuestList =
  private GuestList of Guest list with
    static member none = GuestList []
    static member create guests = specModel GuestList guests {
      unique (fun g -> g.Name) "guest list requires unique guest names" }