(defmacro negatef (place &environment env)
  "Replaces the value of PLACE with its logical negation."
  (multiple-value-bind (vars vals store-vars writer-form reader-form)
      (get-setf-expansion place env)
    `(let* (,@(mapcar #'list vars vals)
            (,(car store-vars) (not ,reader-form)))
       ,writer-form)))