Xmonad/Config archive/Template xmonad.hs
From HaskellWiki
< Xmonad | Config archive
Use a template file for your xmonad version from the Xmonad/Config_archive
% xmonad --version
will tell you what release version you have. If you are running from darcs hopefully you know it already, since darcs will still show the version of the latest release.
You also may have a version that came with your installation somewhere like $docdir/xmonad/man/xmonad.hs or with the xmonad source. Often /usr/share/doc is $docdir.