Good Haskell Style

Johan Bockgård bojohan+news at
Fri Aug 17 07:47:52 EDT 2007

Simon Marlow <simonmarhaskell at> writes:

> While we're on emacs... I know I can colour trailing whitespace
> differently, but that's just annoying.

You could use something more discreet, like colored underlines.

> What I want is: on lines that I edit, remove the trailing whitespace
> (and if I undo the edit, put the whitespace back too). Is there
> something that does that?

    ;; Difficulties are that a) in general changes doesn't necessarily
    ;; happen at the location of point, and OTOH b) commands can
    ;; temporarily move point behind the scenes, but c) we don't want
    ;; characters do disappear under our feet (point) . Try to do
    ;; something sensible.
    (defun line-delete-trailing-whitespace (beg end len)
      (unless (or (eolp) undo-in-progress)
          (delete-char (- (skip-chars-backward " \t" end))))))

    ;; Buffer local, use a mode hook
    (add-hook 'after-change-functions 'line-delete-trailing-whitespace nil t)

    ;; To see what's going on
    (setq show-trailing-whitespace t)

Johan Bockgård

More information about the Libraries mailing list