[xmonad] Managehook which only shifts window if workspace is empty
jochen.keil at gmail.com
Sun Feb 12 00:17:26 CET 2012
-----BEGIN PGP SIGNED MESSAGE-----
On 02/11/2012 11:46 PM, Toby Cubitt wrote:
> 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'"
you probally want to try "whenX" then.
You can easily the test if a workspace is empty like this:
MonadState XState m => WorkspaceId -> m Bool
\t -> gets $ elem t . map S.tag
. filter (isNothing . S.stack)
. S.workspaces . windowset
> 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
> 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
XMonad is documented on xmonad.org as annotated source files. There
are also some documents describing how to write extensions/hooks.
I don't have the links at hand atm, but I think you'll find them
Aaaaaaaaand.. there's always the source. :)
> 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.
For learning Haskell from my experiences I can recommend "Real World
Haskell", reading xmonad's source, and hacking on xmonad..
Sorry for the noise. As it happened many times before I replied only
the sender and forgot to cc the list.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)
-----END PGP SIGNATURE-----
More information about the xmonad