anchor.diff:  
   // Optimization ---------------------------------------------------------------
   
  +// Remove 'this' bindings from lambdas when it is not used in body
  +let RemoveUnusedThis expr =
  +    let bound = HashSet()
  +    let rec rem expr =
  +        match expr with
  +        | Lambda (Some this, args, body) -> 
  +            bound.Add this |> ignore
  +            let bodyTr = Transform rem body
  +            if bound.Contains this then
  +                 bound.Remove this |> ignore
  +                 Lambda (None, args, bodyTr)
  +            else
  +                 Lambda (Some this, args, bodyTr)
  +        | Var v when bound.Contains v ->
  +            bound.Remove v |> ignore
  +            expr
  +        | _ -> Transform rem expr  
  +
  +    rem expr
  +
   /// Transforms local Let- or LetRecursive-bound curried lambda functions to
   /// multi-argument functions when such transformations are possible - the
   /// functions are strictly local, do not escape the scope, and are always
  
positive.code:                     | _ -> expr
          | Sequential (a, b) when isPure a ->
              b
          | Sequential (VarSet (returnVal, NewObject objFields), Sequential (propSetters, Var v)) when v = returnVal ->
              let rec getSetters acc e =
                  match e with
                  | Constant Null -> Some acc
                  | Sequential (more, Unary (UnaryOperator.``void``, FieldSet (Var v, Constant (String field), value)))
                  | Sequential (more, FieldSet (Var v, Constant (String field), value)) ->
                      getSetters ((field, value) :: acc) more
                  | _ -> None
              match getSetters [] propSetters with
              | Some s -> NewObject (objFields @ s)
              | _ -> expr
          | _ ->
              expr
  
  
negative.code: let Optimize expr =
      expr
      |> AlphaNormalize
      |> RemoveUnusedThis
      |> Uncurry
      |> RemoveLoops
      |> CollectObjLiterals
      |> Simplify
  
  // Elaboration ----------------------------------------------------------------
  