Wm -> W, all good monads have single capital letter names. comment the W.hs file

Main.hs

@@ -25,7 +25,7 @@ import Graphics.X11.Xlib.Extras
 import System.Process (runCommand)
 import System.Exit
 
-import Wm
+import W
 
 ------------------------------------------------------------------------
 
@@ -35,7 +35,7 @@ import Wm
 main :: IO ()
 main = do
     dpy <- openDisplay ""
-    runWm realMain $ WmState
+    runW realMain $ WState
             { display = dpy
             , screenWidth  = displayWidth  dpy (defaultScreen dpy)
             , screenHeight = displayHeight dpy (defaultScreen dpy)
@@ -46,7 +46,7 @@ main = do
 --
 -- Grab the display and input, and jump into the input loop
 --
-realMain :: Wm ()
+realMain :: W ()
 realMain = do
     dpy <- getDisplay
     let screen = defaultScreen dpy
@@ -59,7 +59,7 @@ realMain = do
 --
 -- The main event handling loop
 --
-loop :: Wm ()
+loop :: W ()
 loop = do
     dpy <- getDisplay
     forever $ do
@@ -71,7 +71,7 @@ loop = do
 --
 -- The event handler
 -- 
-handler :: Event -> Wm ()
+handler :: Event -> W ()
 handler (MapRequestEvent {window = w}) = manage w
 
 handler (DestroyWindowEvent {window = w}) = do
@@ -90,7 +90,7 @@ handler _ = return ()
 --
 -- switch focus (?)
 --
-switch :: Wm ()
+switch :: W ()
 switch = do
     ws' <- getWindows
     case viewl ws' of
@@ -102,13 +102,13 @@ switch = do
 --
 -- | spawn. Launch an external application
 --
-spawn :: String -> Wm ()
+spawn :: String -> W ()
 spawn = io_ . runCommand
 
 --
 -- | Keys we understand.
 --
-keys :: [(KeyMask, KeySym, Wm ())]
+keys :: [(KeyMask, KeySym, W ())]
 keys =
     [ (mod1Mask .|. shiftMask, xK_Return, spawn "xterm")
     , (controlMask,            xK_space,  spawn "gmrun")
@@ -119,7 +119,7 @@ keys =
 --
 -- | grabkeys. Register key commands
 --
-grabkeys :: Wm ()
+grabkeys :: W ()
 grabkeys = do
     dpy <- getDisplay
     root <- io $ rootWindow dpy (defaultScreen dpy)
@@ -130,7 +130,7 @@ grabkeys = do
 --
 --
 --
-manage :: Window -> Wm ()
+manage :: Window -> W ()
 manage w = do
     trace "manage"
     d <- getDisplay
@@ -144,7 +144,7 @@ manage w = do
 --
 -- refresh the windows
 --
-refresh :: Wm ()
+refresh :: W ()
 refresh = do
     v  <- getWindows
     case viewl v of

W.hs

@@ -0,0 +1,98 @@
+-----------------------------------------------------------------------------
+-- |
+-- 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.
+--
+
+module W where
+
+import Data.Sequence
+import Control.Monad.State
+import System.IO (hFlush, hPutStrLn, stderr)
+import Graphics.X11.Xlib
+
+--
+-- | WState, the window manager state.
+-- Just the display, width, height and a window list
+--
+data WState = WState
+    { display       :: Display
+    , screenWidth   :: !Int
+    , screenHeight  :: !Int
+    , windows       :: Seq Window
+    }
+
+-- | The W monad, a StateT transformer over IO encapuslating the window
+-- manager state
+--
+newtype W a = W (StateT WState IO a)
+    deriving (Functor, Monad, MonadIO)
+
+-- | Run the W monad, given a chunk of W monad code, and an initial state
+-- Return the result, and final state
+--
+runW :: W a -> WState -> IO (a, WState)
+runW (W m) = runStateT m
+
+withIO :: (forall b. (a -> IO b) -> IO b) -> (a -> W c) -> W c
+withIO f g = do
+    s <- W get
+    (y, t) <- io (f (flip runW s . g))
+    W (put t)
+    return y
+
+--
+-- | 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 ()
+
+--
+-- | A 'trace' for the W monad
+--
+trace :: String -> W ()
+trace msg = io $ do
+    hPutStrLn stderr msg
+    hFlush stderr
+
+-- ---------------------------------------------------------------------
+-- Getting at the window manager state
+
+-- | Return the current dispaly
+getDisplay          :: W Display
+getDisplay          = W (gets display)
+
+-- | Return the current windows
+getWindows          :: W (Seq Window)
+getWindows          = W (gets windows)
+
+-- | Return the screen width
+getScreenWidth      :: W Int
+getScreenWidth      = W (gets screenWidth)
+
+-- | Return the screen height
+getScreenHeight     :: W Int
+getScreenHeight     = W (gets screenHeight)
+
+-- | Set the current window list
+setWindows          :: Seq Window -> W ()
+setWindows x        = W (modify (\s -> s {windows = x}))
+
+-- | Modify the current window list
+modifyWindows       :: (Seq Window -> Seq Window) -> W ()
+modifyWindows f     = W (modify (\s -> s {windows = f (windows s)}))

Wm.hs

@@ -1,70 +0,0 @@
------------------------------------------------------------------------------
--- |
--- 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
-
---
--- | Lift an IO action into the Wm monad
---
-io :: IO a -> Wm a
-io = liftIO
-
---
--- | Lift an IO action into the Wm monad, discarding any result
---
-io_ :: IO a -> Wm ()
-io_ f = liftIO f >> return ()
-
-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)}))