[xmonad] silly behavior of killWord in XMonad.Prompt

Brent Yorgey byorgey at seas.upenn.edu
Thu May 10 19:46:27 CEST 2012

OK, I just pushed this patch:

Thu May 10 13:43:17 EDT 2012  Brent Yorgey <byorgey at cis.upenn.edu>
  * updates to XMonad.Prompt re: word-oriented commands
    + change killWord and moveWord to have emacs-like behavior: first
      move past/kill consecutive whitespace, then move past/kill
      consecutive non-whitespace.
    + create variants killWord' and moveWord' which take a predicate
      specifying non-word characters.
    + create variants defaultXPKeymap' and emacsLikeXPKeymap' which
      take the same sort of predicate, which is applied to all
      keybindings with word-oriented commands.

My config now looks something like 

    myXPConfig = defaultXPConfig
	{ fgColor = "#a8a3f7"
	, bgColor = "#3f3c6d"
	, promptKeymap = emacsLikeXPKeymap' myWordSep

    myWordSep :: Char -> Bool
    myWordSep c = isSpace c || c == '/'



On Tue, Apr 24, 2012 at 10:07:57AM -0400, Brent Yorgey wrote:
> I realized today that the behavior of killWord from XMonad.Prompt is
> surprising to me.  In particular, when you iterate killWord, it
> deletes first a word, then a space, then the next word, then the next
> space, and so on.  I (an emacs user) expect killWord to delete a word
> AND any whitespace that happens to come before it.  (Hmm... I tested
> with vim and it seems that 'dw' deletes a word along with any TRAILING
> whitespace.  So emacs and vim differ here... but the point is that
> killWord emulates neither.)
> I looked into it and it turns out that the behavior of killWord is
> even sillier than I thought. It deletes an entire word of
> non-whitespace characters *or a single space*. (So if there are
> multiple spaces you have to call killWord once for each space before
> you finally get to delete the word that comes after.)  And if the next
> character is a tab it doesn't delete anything at all!
> For concreteness, here's the change I made:
> diff -rN old-XMonadContrib/XMonad/Prompt.hs
> new-XMonadContrib/XMonad/Prompt.hs
> 525,528c525
> <       delNextWord w =
> <           case w of
> <             ' ':x -> x
> <             word  -> snd . break isSpace $ word
> ---
> >       delNextWord   = snd . break isSpace . dropWhile isSpace
> Thoughts?  If anyone really likes the old behavior then I can make two
> versions.  Or if there is consensus that the old behavior is silly and
> the new behavior is better, then I'll just push the above change.  I
> could also be talked into swapping the order of the break and
> dropWhile in order to emulate vim; I don't really care as long as it's
> one of the two.
> -Brent
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