module DataAccess =
  // Would it simplify anything by a lot if WsdlService could generate ServiceTypes as records instead of classes?
  type Service40 = WsdlService<My40ServiceUrl>
  type Service41 = WsdlService<My41ServiceUrl>
  type Service42 = WsdlService<My42ServiceUrl>

// All the ticketXXToDomain functions look like they can be less copy-paste, but how?
// Still, I think this F# approach is MUCH better than the mega project we have where WCF SvcUtil.exe
// generate everything for every version and we check that in to source.
module VersionMappers =
  module Ticket =
    let ticket40ToDomain (t : Service40.ServiceTypes.Ticket) =
      MyCSharpProject.Pocos.Ticket(
        TicketId = t.TicketId
        // with 10+ other fields
        TicketType = t.TicketType)
    let ticket41ToDomain (t : Service41.ServiceTypes.Ticket) =
      MyCSharpProject.Pocos.Ticket(
        TicketId = t.TicketId
        // with 10+ other fields
        TicketType = t.TicketType)
    let ticket42ToDomain (t : Service42.ServiceTypes.Ticket) =
      MyCSharpProject.Pocos.Ticket(
        TicketId = t.TicketId
        // with 10+ other fields
        TicketType = t.TicketType)

module CanThisPseudoCodeBeReal =
  type Services =
    | V40 of Service40
    | V41 of Service41
    | V42 of Service42
  let ticketToDomain (t : 'a when 'a is one of Services) =
    MyCSharpProject.Pocos.Ticket(...)