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|
-----------------------------------------------------------------------------
-- |
-- Module : Wm.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 Wm monad, a state monad transformer over IO, for the window manager state.
--
module Wm where
import Data.Sequence
import Control.Monad.State
import System.IO (hFlush, hPutStrLn, stderr)
import Graphics.X11.Xlib
data WmState = WmState
{ display :: Display
, screenWidth :: !Int
, screenHeight :: !Int
, windows :: Seq Window
}
newtype Wm a = Wm (StateT WmState IO a)
deriving (Monad, MonadIO{-, MonadState WmState-})
runWm :: Wm a -> WmState -> IO (a, WmState)
runWm (Wm m) = runStateT m
io :: IO a -> Wm a
io = liftIO
trace msg = io $ do
hPutStrLn stderr msg
hFlush stderr
withIO :: (forall b. (a -> IO b) -> IO b) -> (a -> Wm c) -> Wm c
withIO f g = do
s <- Wm get
(y, s') <- io $ f $ \x -> runWm (g x) s
Wm (put s')
return y
getDisplay = Wm (gets display)
getWindows = Wm (gets windows)
getScreenWidth = Wm (gets screenWidth)
getScreenHeight = Wm (gets screenHeight)
setWindows x = Wm (modify (\s -> s {windows = x}))
modifyWindows :: (Seq Window -> Seq Window) -> Wm ()
modifyWindows f = Wm (modify (\s -> s {windows = f (windows s)}))
|
