anchor.diff:              | Right struct (simulant, world) ->
                   let stream = Stream.make (atooa simulant.SimulantAddress ->>- Events.SimulantChange propertyName)
                   let stream =
  -                    Stream.mapEvent (fun evt world ->
  -                        match (evt.Data : obj) with
  +                    Stream.mapEvent (fun (evt : Event<obj, _>) world ->
  +                        match evt.Data with
                           | :? ChangeData as changeData ->
                               let simulant = evt.Publisher :?> Simulant
                               match World.tryGetSimulantProperty changeData.PropertyName simulant world with
  
positive.code:             | struct ([|String propertyName|], world)
              | struct ([|Keyword propertyName|], world) -> World.evalGet fnName propertyName None originOpt world
              | struct ([|_|], world) -> struct (Violation (["InvalidArgumentType"; String.capitalize fnName], "Application of " + fnName + " requires a String or Keyword for the first argument, and an optional Relation for the second.", originOpt), world)
              | struct (_, world) -> struct (Violation (["InvalidArgumentCount"; String.capitalize fnName], "Incorrect number of arguments for application of '" + fnName + "'; 1 or 2 arguments required.", originOpt), world)
  
          static member internal evalGetAsStreamExtrinsic fnName exprs originOpt world =
              match World.evalManyInternal exprs world with
  
negative.code: 
          static member internal evalMonitor fnName evaledArg evaledArg2 originOpt world =
              match evaledArg with
              | Violation _ as error -> struct (error, world)
              | Binding _
              | Fun _ ->
                  match evaledArg2 with
                  | Violation _ as error -> struct (error, world)
                  | String str
                  | Keyword str ->
                      let eventAddress = Address.makeFromString str
                      let context = World.getScriptContext world
                      let world = World.evalMonitor5 evaledArg eventAddress context world
                      struct (Unit, world)
                  | _ -> struct (Violation (["InvalidArgumentType"; String.capitalize fnName], "Function '" + fnName + "' requires a Relation for its 2nd argument.", originOpt), world)
              | _ -> struct (Violation (["InvalidArgumentType"; String.capitalize fnName], "Function '" + fnName + "' requires a Function for its 1st argument.", originOpt), world)
  
          /// Attempt to evaluate the scripting prelude.
  