Modifying constructor for design structures.
(change-design x [:modalist <modalist>] [:top <top>])
This is an often useful alternative to make-design.
We construct a new design structure that is a copy of
This is an ordinary
(defmacro change-design (x &rest args) (std::change-aggregate 'design x args '((:modalist . design->modalist) (:top . design->top)) 'change-design 'nil))