anchor.diff:  
   (eval-when (:compile-toplevel :load-toplevel :execute)
   
  -  (defmacro left-fold (x &body forms)
  +  (defmacro -> (x &body forms)
       "Inserts x as the second item in the first forms,
   making a list of it if it is not a list already. If there are more
   formss, inserts the first forms as the second item in second forms, etc.
  
positive.code:                  `(,(car first) ,x ,@(cdr first))
                   `(,first ,x))))
            (t
             `(left-fold (left-fold ,x ,(car forms)) ,@(cdr forms)))))
  
    ) ;end of eval-when
  
  
negative.code:                (rotate middle-rotor))
               (rotate right-rotor))
         :collect (char *alphabet*
                        (-> char-num
                          (convert plugboard)
                          (convert right-rotor)
                          (convert middle-rotor)
  