anchor.diff:                 ;; function to call
                  (implicit-uniform-upload-func #'fallback-iuniform-func)
                  ;;
  -               ;; {todo} explain
  +               ;; vars for the uniform locations
                  ,@(mapcar λ`(,(first _) -1)
                            (mapcat #'let-forms uniform-assigners))
                  ;;
  
positive.code:        (let ((*standard-output* (make-string-output-stream)))
           (handler-bind ((warning #'muffle-warning))
             (eval (%defpipeline-gfuncs
                    ',name ',gpipe-args ',context t)))))))
  
  (defun+ %update-spec (name stage-pairs context)
    (update-pipeline-spec
  
negative.code:   (%defpipeline-gfuncs name gpipe-args context))
  
  (defun+ %defpipeline-gfuncs
      (name gpipe-args context)
    ;;
    ;; {todo} explain
    (destructuring-bind (stage-pairs post) (parse-gpipe-args gpipe-args)
  