anchor.diff:              let monitorFilter =
                   fun a a2Opt _ ->
                       match a2Opt with
  -                    | Some a2 -> not (refEq a a2 || genEq a a2)
  +                    | Some a2 -> a =/= a2
                       | None -> true
               let subscription = fun _ world ->
                   let mapGeneralized = Lens.get lensGeneralized world
  
positive.code:             let monitorMapper =
                  fun a _ world ->
                      let b =
                          if refEq a.Value monitorResult || genEq a.Value monitorResult
                          then match sieveResultOpt with Some b -> b | None -> sieve (lens.Get world)
                          else sieve (lens.Get world)
                      monitorResult <- a.Value
  
negative.code:             let lensGeneralized =
                  Lens.mapWorld (fun a world ->
                      let (b, c) =
                          if a === lensResult then
                              match (sieveResultOpt, unfoldResultOpt) with
                              | (Some b, Some c) -> (b, c)
                              | (Some b, None) -> let c = unfold b world in (b, c)
  