anchor.diff:  
   (defmethod show ((a number))
     #{ (~a).toString() #})
  -
  -(define-stupid-show compound-form)
  -(define-stupid-show class)
  -(define-stupid-show function)
  -(define-stupid-show list)
  -(define-stupid-show number-form)
  -(define-stupid-show string-dict)
  -(define-stupid-show string-form)
  -(define-stupid-show symbol-form)
   
   ;;;; Numbers
   
  
positive.code: 
  (defgeneric show (object))
  
  (eval-when-compile
    (defun show-unreadable (class-name &optional (more ""))
      (string-concat "#(" (symbol-name class-name) more ")")))
  
  (defmacro define-stupid-show (class-name)
    #`(defmethod show ((a ,class-name))
        ,(string-to-form (show-unreadable class-name))))
  
  (defmethod show ((a object))
    #{ JSON.stringify(~a) #})
  
  
negative.code: ;; simple-error is defined in JS
  (set-superclass (class simple-error) (class error))
  (defmethod show ((s simple-error))
    (string-concat (simple-error-message s) (simple-error-arg s)))
  
  (defclass control-error (error))
  
  