dired-ex.el

;;;===================================================================
;;; override dired-flag-backup-files with
;;; dired-flag-backup-files-and-lisp-fasl-files

(defcustom dired-lisp-fasl-files-regexp
  ;; SBCL  -- .fasl
  ;; CCL   --
  ;; CLISP --
  ;; ECL   -- .o (and perhaps others)
  (concat (regexp-opt
	   '(".fasl" ".o"))
	  "\\'")
  "Regular expression to match \"garbage\" files for `dired-flag-lisp-fasl-files'."
  :type 'regexp
  :group 'dired)

(defun dired-flag-lisp-fasl-files ()
  "Flag for deletion all files that match `dired-flag-lisp-fasl-files'."
  (interactive)
  (dired-flag-files-regexp dired-lisp-fasl-files-regexp))

(defun dired-flag-backup-files-and-lisp-fasl-files (&optional unflag-p)
  "Flag all backup files (names ending with `~') for deletion.
With prefix argument, FLAG ALSO LISP FASL FILES (NOT UNMARK OR UNFLAG THESE FILES)."
  (interactive "P")
  ;; note: override dired-flag-backup-files, i.e. the original means calling
  ;; (dired-flag-backup-files unflag-p)
  (prog1 (dired-flag-backup-files nil)
    (when unflag-p ; note: in fact, unflag-p should be renamed as with-fasl-files-p
      (dired-flag-lisp-fasl-files))))

(add-hook 'dired-load-hook
  (lambda ()
    (define-key dired-mode-map "~" 'dired-flag-backup-files-and-lisp-fasl-files)))