[xmonad] DynamicLog improvements and new contrib module, XMonad.Util.Loggers

[Brent Yorgey]

On Wed, Feb 20, 2008 at 2:24 AM, Andrea Rossato <andrea.rossato at unibz.it>
wrote:

>
> And so your plan of world domination has been eventually revealed! You
> want to get rid of the very reasons why xmobar had to be written! I'll
> fight it to death!!
> ;)
>
> I'm just kidding... very nice idea, indeed.
>

Muahahaha!!!  Hehe, of course, that's not really my intention.  Rest assured
that my REAL plan of world domination has yet to be revealed.  As Spencer
points out, there are still good reasons to use xmobar.


>
> Just one question: why Maybe String? I had a very quick read at your
> code, but as far as I understand using 'catMaybes' means that 'Just
> []' and 'Nothing' have the very same meaning. Am I wrong?
>

Hmm... well, using 'catMaybes' doesn't do that: catMaybes [Just "abc",
Nothing] --> ["abc"], but catMaybes [Just "abc", Just ""] --> ["abc", ""].
But in the end I guess you're right, since the status bar output function
filters out the empty string (in particular the "sepBy" function filters out
the null string).  I didn't realize this before, and I wonder whether it is
really the correct behavior.  My intention was to allow for two different
cases, one in which a logger does not want to output anything (or gives an
error), and another in which the logger explicitly wants to output the empty
string. For example, maybe you have a logger which only outputs something
some of the time, but when it is not outputting anything you still want a
blank space where it would have been.  I don't know, it's not really very
important either way, I guess. =)

-Brent
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