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author | Don Stewart <dons@cse.unsw.edu.au> | 2007-03-08 13:05:36 +0100 |
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committer | Don Stewart <dons@cse.unsw.edu.au> | 2007-03-08 13:05:36 +0100 |
commit | 4aa9591695e800730109aba87ca84e49dfc4e334 (patch) | |
tree | 39a8ab61176d243a3c155f58f637aa921920842b /WMonad.hs | |
parent | fe3c72ae8f541f6732e525b096deb99ccecd4bd2 (diff) | |
download | metatile-4aa9591695e800730109aba87ca84e49dfc4e334.tar metatile-4aa9591695e800730109aba87ca84e49dfc4e334.zip |
move W -> WMonad
darcs-hash:20070308120536-9c5c1-cd1cf451dd9a5a75f5372bdd310bb5a485bf2fec
Diffstat (limited to 'WMonad.hs')
-rw-r--r-- | WMonad.hs | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/WMonad.hs b/WMonad.hs new file mode 100644 index 0000000..0c4f913 --- /dev/null +++ b/WMonad.hs @@ -0,0 +1,84 @@ +----------------------------------------------------------------------------- +-- | +-- Module : W.hs +-- Copyright : (c) Spencer Janssen 2007 +-- License : BSD3-style (see LICENSE) +-- +-- Maintainer : sjanssen@cse.unl.edu +-- Stability : unstable +-- Portability : not portable, uses cunning newtype deriving +-- +----------------------------------------------------------------------------- +-- +-- The W monad, a state monad transformer over IO, for the window +-- manager state, and support routines. +-- + +module WMonad where + +import StackSet + +import Control.Monad.State +import System.IO +import System.Process (runCommand) +import Graphics.X11.Xlib (Display,Window) + +-- | WState, the window manager state. +-- Just the display, width, height and a window list +data WState = WState + { display :: Display + , screenWidth :: {-# UNPACK #-} !Int + , screenHeight :: {-# UNPACK #-} !Int + , workspace :: {-# UNPACK #-} !WorkSpace -- ^ workspace list + } + +type WorkSpace = StackSet Window + +-- | The W monad, a StateT transformer over IO encapuslating the window +-- manager state +newtype W a = W { unW :: StateT WState IO a } + deriving (Functor, Monad, MonadIO, MonadState WState) + +-- | Run the W monad, given a chunk of W monad code, and an initial state +-- Return the result, and final state +runW :: WState -> W a -> IO (a, WState) +runW st a = runStateT (unW a) st + +-- | Lift an IO action into the W monad +io :: IO a -> W a +io = liftIO + +-- | Lift an IO action into the W monad, discarding any result +io_ :: IO a -> W () +io_ f = liftIO f >> return () + +-- | Run an action forever +forever :: (Monad m) => m a -> m b +forever a = a >> forever a + +-- | spawn. Launch an external application +spawn :: String -> W () +spawn = io_ . runCommand + +-- | A 'trace' for the W monad. Logs a string to stderr. The result may +-- be found in your .xsession-errors file +trace :: String -> W () +trace msg = io $ do + hPutStrLn stderr msg + hFlush stderr + +-- | Modify the workspace list +modifyWorkspace :: (WorkSpace -> WorkSpace) -> W () +modifyWorkspace f = do + modify $ \s -> s { workspace = f (workspace s) } + ws <- gets workspace + trace (show $ ws) + +-- | Like 'when' but for (WorkSpace -> Maybe a) +whenJust :: (WorkSpace -> Maybe a) -> (a -> W ()) -> W () +whenJust mg f = do + ws <- gets workspace + case mg ws of + Nothing -> return () + Just w -> f w + |