It was reported in #haskell that xmonad-contrib does not compile with ghc HEAD. We tracked it down to (>>>) no longer being exported from Control.Arrow. It is now a member of the Category superclass and defined in Control.Category but it is no longer exported from Control.Arrow. It seems that any code that does not define its own arrow instances would still be able to work unchanged if (>>>) and (<<<) were just to be re-exported from Control.Arrow. So here's a completely untested patch to do that. Duncan Fri Apr 25 10:11:13 BST 2008 Duncan Coutts <duncan.coutts@worc.ox.ac.uk> * Re-export (>>>), (<<<) from Control.Arrow for compatability They're now defined in Control.Category but all existing code expects them o be exported from Control.Arrow. For example, this should unbreak xmonad-contrib.