anchor.diff:        ((cons (cons symbol))
          (destructuring-bind ((operator &rest opargs) &rest args) form
            (expand operator opargs args)))
  -      (string `(write-string ,form ,stream))
  -      (character `(write-char ,form ,stream))
  -      (number `(write ,form :stream ,stream))
  +      (string form)
  +      ((or character number) (write-to-string form :escape nil))
         (t form))))
   
  -(defun formatexpand-forms (forms ~ stream)
  +(defun formatexpand-forms-partially (forms ~ stream)
     (mapcar (lambda (form)
  -            (formatexpand form ~ stream))
  +            (formatexpand-partially form ~ stream))
             forms))
   
   (defmacro ~format ((~ &optional stream) &body body)
     (let* ((stream-var (gensym (string '#:stream))))
  -    `(with-~format-stream (,stream-var ,stream)
  +    `(with-~format-stream (,stream-var
  +                           ,@(when stream (list :stream stream)))
          ,@(formatexpand-forms body ~ stream-var))))
   
   (defmacro define-~format (name
  
positive.code:                             ,@body)))))))
  
  (define-~format progn (~ stream) (&rest forms)
    `(progn ,@(formatexpand-forms forms ~ stream)))
  
  (define-~format if (~ stream) (test then &optional (else nil elsep))
    `(if ,test
         ,(formatexpand then ~ stream)
         ,@(when elsep (list (formatexpand else ~ stream)))))
  
  (define-~format when (~ stream) (test &rest body)
    `(when ,test
       ,@(formatexpand-forms body ~ stream)))
  
  (define-~format unless (~ stream) (test &rest body)
    `(unless ,test
       ,@(formatexpand-forms body ~ stream)))
  
  (define-~format cond (~ stream) (&rest clauses)
    `(cond ,@(mapcar
              (lambda (clause)
                (cons (first clause)
                      (formatexpand-forms (rest clause) ~ stream)))
                     clauses)))
  
  (eval-when (:compile-toplevel :load-toplevel :execute)
  
negative.code:         (lambda (binding)
            (if (consp binding)
                (cons (first binding)
                      (formatexpand-forms-partially (rest binding) ~ stream))
                binding))
          bindings)
        ,@body)))
  