From 813264ca0d49d271b919f57a3f6d830dc8034ec8 Mon Sep 17 00:00:00 2001
From: Don Stewart <dons@cse.unsw.edu.au>
Date: Wed, 7 Mar 2007 06:50:07 +0100
Subject: refactoring. less code

darcs-hash:20070307055007-9c5c1-2dc9d077773b25f22954c41856e670f3b5583e9f
---
 W.hs | 49 +++++++++++++++++++++----------------------------
 1 file changed, 21 insertions(+), 28 deletions(-)

(limited to 'W.hs')

diff --git a/W.hs b/W.hs
index 5bacfea..deed0e6 100644
--- a/W.hs
+++ b/W.hs
@@ -20,64 +20,42 @@ import System.IO
 import Graphics.X11.Xlib
 import Control.Monad.State
 
---
 -- | WState, the window manager state.
 -- Just the display, width, height and a window list
---
 data WState = WState
     { display       :: Display
     , screenWidth   :: !Int
     , screenHeight  :: !Int
-    , windows       :: Windows
+    , windows       :: !Windows
     }
 
 type Windows = [Window]
 
 -- | The W monad, a StateT transformer over IO encapuslating the window
 -- manager state
---
-newtype W a = W (StateT WState IO a)
+newtype W a = W { unW :: 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
+runW :: WState -> W a -> IO (a, WState)
+runW st a = runStateT (unW a) st
 
-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
---
+-- | 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
 
---
--- | Run an action forever
---
-forever :: (Monad m) => m a -> m b
-forever a = a >> forever a
-
 -- ---------------------------------------------------------------------
 -- Getting at the window manager state
 
@@ -104,3 +82,18 @@ setWindows x        = W (modify (\s -> s {windows = x}))
 -- | Modify the current window list
 modifyWindows       :: (Windows -> Windows) -> W ()
 modifyWindows f     = W (modify (\s -> s {windows = f (windows s)}))
+
+-- ---------------------------------------------------------------------
+-- Generic utilities
+
+-- | Run an action forever
+forever :: (Monad m) => m a -> m b
+forever a = a >> forever a
+
+-- | Add an element onto the end of a list
+snoc :: [a] -> a -> [a]
+snoc xs x = xs ++ [x]
+
+-- | Rotate a list one element
+rotate []     = []
+rotate (x:xs) = xs `snoc` x
-- 
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