(= (bool-not x)
   (case x
     (true-t false)
     (false-t true)))

(assert (eq (bool-not true) false))
(assert (eq (bool-not false) true))

(= (bool-not-2 x)
   (case x
     (true-t false)
     (_ true)))

(assert (eq (bool-not-2 true) false))
(assert (eq (bool-not-2 false) true))