[xmonad] xmonad and ghc 6.12

[Don Stewart]

byorgey:
> So, let's talk about plans for xmonad and ghc 6.12.  I am currently
> building xmonad and xmonad-contrib on ghc 6.12.1rc2 and it works fine,
> except I get a lot of warnings, which fall into three main categories:
> 
>   * Warnings about using base-3 instead of base-4.  Currently xmonad
>     doesn't build with base-4 because of the Exception
>     vs. OldException thing.  What's our plan for dealing with this?
>     We should switch to using the extensible exception stuff, but how
>     do we continue to support base-3? (*Should* we continue to support
>     it?)

base-3 is around for at least one more release. I would propose we make
the change to base 4 in the next stable release.

>   * Warnings about redundant imports; apparently 6.12 is more
>     aggressive about noticing these.  These can be cleaned up, which
>     is probably a good idea anyway.  Or, if people don't like this for
>     some reason, we can disable this warning.

If it is accurate, there's no harm being tidy.
  
>   * Lots of warnings about actions which return something other than
>     () but whose results are neither bound nor explicitly discarded.
>     As discussed on IRC the right thing to do here is probably to just
>     pass -fno-warn-unused-do-bind to ghc (as opposed to "fixing" all
>     of these).

Warning are annoying :)

-- Don