Experimental support for a beefier restart.

Config.hs

@@ -169,7 +169,7 @@ keys = M.fromList $
     , ((modMask .|. shiftMask, xK_c     ), kill)
 
     , ((modMask .|. shiftMask, xK_q                     ), io $ exitWith ExitSuccess)
-    , ((modMask .|. shiftMask .|. controlMask, xK_q     ), restart)
+    , ((modMask .|. shiftMask .|. controlMask, xK_q     ), restart Nothing False)
 
     -- Cycle the current tiling order
     , ((modMask,               xK_Return), swap)

Main.hs

@@ -17,6 +17,8 @@ import Data.Bits
 import qualified Data.Map as M
 import Control.Monad.Reader
 
+import System.Environment (getArgs)
+
 import Graphics.X11.Xlib hiding (refreshKeyboardMapping)
 import Graphics.X11.Xlib.Extras
 import Graphics.X11.Xinerama    (getScreenInfo)
@@ -41,8 +43,12 @@ main = do
     xinesc <- getScreenInfo dpy
     nbc    <- initcolor normalBorderColor
     fbc    <- initcolor focusedBorderColor
+    args <- getArgs
 
-    let safeLayouts = case defaultLayouts of [] -> (full, []); (x:xs) -> (x, xs)
+    let winset | ("--resume" : s : _) <- args
+               , [(x, "")]            <- reads s = x
+               | otherwise = new (fromIntegral workspaces) (fromIntegral $ length xinesc)
+        safeLayouts = case defaultLayouts of [] -> (full, []); (x:xs) -> (x, xs)
         cf = XConf
             { display       = dpy
             , theRoot       = rootw
@@ -53,7 +59,7 @@ main = do
             , focusedBorder = fbc
             }
         st = XState
-            { windowset     = new (fromIntegral workspaces) (fromIntegral $ length xinesc)
+            { windowset     = winset
             , layouts       = M.fromList [(w, safeLayouts) | w <- [0 .. W workspaces - 1]]
             , xineScreens   = xinesc
             , dimensions    = (fromIntegral (displayWidth dpy dflt),

XMonad.hs

@@ -140,13 +140,21 @@ spawn x = io $ do
     getProcessStatus True False pid
     return ()
 
--- | Restart xmonad by exec()'ing self. This doesn't save state and xmonad has
+-- | Restart xmonad via exec().
--- to be in PATH for this to work.
+--
-restart :: X ()
+-- If the first parameter is 'Just name', restart will attempt to execute the
-restart = io $ do
+-- program corresponding to 'name'.  Otherwise, xmonad will attempt to execute
-    prog      <- getProgName
+-- the name of the current program.
-    args      <- getArgs
+--
-    catch (executeFile prog True args Nothing) (const $ return ())
+-- When the second parameter is 'True', xmonad will attempt to resume with the
+-- current window state.
+restart :: Maybe String -> Bool -> X ()
+restart mprog resume = do
+    prog  <- maybe (io $ getProgName) return mprog
+    args  <- io $ getArgs
+    args' <- if resume then gets (("--resume":) . return . show . windowset) else return []
+    io $ catch (executeFile prog True (args ++ args') Nothing)
+               (const $ return ()) -- ignore executable not found exception
 
 -- | Run a side effecting action with the current workspace. Like 'when' but
 whenJust :: Maybe a -> (a -> X ()) -> X ()