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

Brent Yorgey byorgey at gmail.com
Wed Feb 20 07:04:33 EST 2008

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

> 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. =)

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