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GNU Emacs 18.55.18 of Thu Mar 29 1990 on shelby.Stanford.EDU (berkeley-unix)

The backquote (`) function can sometimes modify its argument.  Here is
an example:

(defun foo ()
  (\`
   (progn (\, nil) (\,@ (list)))))
=> foo
(symbol-function 'foo)
=> (lambda nil (\` (progn (\, nil) (\,@ (list)))))
(foo)
=> (progn nil)
(symbol-function 'foo)
=> (lambda nil (\` (progn (\, nil) (\,@ (list nil)))))
(foo)
=> (progn nil nil)

The problem is with a rplacd in the function bq-evalappend; replacing
that function with the following definition:


(defun bq-evalappend (form)
  (cond ((and (listp tailmaker)
	   (listp (car tailmaker))
	   (eq (bq-caar tailmaker) 'list))
	 (setq tailmaker (cons (cons (car (car tailmaker))
				     (cons form (bq-cdar tailmaker)))
			       (cdr tailmaker)))
;	 (rplacd (car tailmaker)
;		 (cons form (bq-cdar tailmaker)))
)
	((= (length tailmaker) 1)
	 (setq tailmaker (cons form tailmaker))
	 (setq state 'cons))
	(t (bq-push (list 'list form) tailmaker))))

(replacing the rplacd with a setq which builds a new list) seems to
solve the problem.

Carl Witty
cwitty@cs.stanford.edu