I'm trying to write a Managehook that only shifts a window to workspace if that workspace is empty. But I'm quickly realising I don't have a good enough grasp of Xmonad types, and Haskell monads in general, to get it to work. So far, the closest I think I've got is the following: myManageHook = [ className =? "mutt" --> doShiftEmpty "email" ] where doShiftEmpty t = when (isEmpty t) (doShift t) isEmpty t = do wsl <- gets $ W.workspaces . windowset let mws = find (\ws -> W.tag ws == t) wsl return $ maybe True (isNothing . W.stack) mws which throws a type error: "Couldn't match expected type `Bool' with actual type `m0 Bool' In the return type of a call of `isEmpty'" I think I vaguely understand the problem, namely that "when" expects a Bool as its first argument, whereas the "return" in isEmpty returns a Bool wrapped inside a monad. But removing the "return" just throws a more confusing type error. Clearly, I'm way out of my depth here, and am doing little better than cargo cult programming. Can someone who understands these things properly explain where I'm going wrong here? More generally, is there a tutorial explaining the Xmonad types and data structures, and how they go together to make up Xmoand? I've been working through some basic Haskell tutorials, but there's still quite a step from understanding a little Haskell, to understanding enough of how Xmonad works to write a simple Managehook action. Toby -- Dr T. S. Cubitt Mathematics and Quantum Information group Department of Mathematics Complutense University Madrid, Spain email: tsc25@cantab.net web: www.dr-qubit.org