List all ESS variables in the current buffer.

list-ess-vars.el

;; From Michael Hannon and Vince Buffalo

(require 'cl)

(defun flatten (list)            ; From `misc-fns.el'.                                                                                                                                                                               
  "Flatten LIST, returning a list with the atoms in LIST at any level.                                                                                                                                                               
  Also works for a consp whose cdr is non-nil.                                                                                                                                                                                                                                                                                                                                                                                                               
  Borrowed from: http://www.emacswiki.org/emacs/lib-requires.el"

  (cond ((null list) nil)
        ((atom list) list)
        (t
         (let ((old list)
               (new ())
               item)
          (while old
            (if (atom old)             ; From consp with non-nil cdr.                                                                                                                                                                
                (setq item old
        	      old nil)
              (setq item (car old)
 	            old (cdr old)))
            ;; Make item atomic.                                                                                                                                                                                                     
            (while (consp item)
              (if (cdr item)
                  (setq old (cons (cdr item) old)))
              (setq item (car item)))
            (setq new (cons item new)))
          (reverse new)))))


(defun make-sep ()
  (list (string ?\n)
        (string ?\n)
        (make-string 48 ?#)
        (string ?\n)
        (string ?\n)))

(defun print-var-desc(next-var)
       (list (flatten (make-sep))
             (describe-variable next-var)))

(let (vars)
  (do-symbols (s) (when (and (boundp s) (eq (string-match "ess-" (symbol-name s)) 0))
                    (push s vars)))
  (insert (format "%s" (flatten (mapcar (lambda (s) (print-var-desc s)) vars)))))