Statically distinguish Workspace and Screen indices

Config.hs

@@ -1,70 +1,69 @@
 module Config where
 
-{-
+--
-xmonad bindings follow mostly the dwm/wmii conventions:
+-- xmonad bindings follow mostly the dwm/wmii conventions:
-
+-- 
-    key combination         action
+--     key combination         action
-    
+--     
-    mod-shift-return        new xterm
+--     mod-shift-return        new xterm
-    mod-p                   launch dmenu
+--     mod-p                   launch dmenu
-    mod-shift-p             launch gmrun
+--     mod-shift-p             launch gmrun
-
+-- 
-    mod-space               switch tiling mode
+--     mod-space               switch tiling mode
-
+-- 
-    mod-tab                 raise next window in stack
+--     mod-tab                 raise next window in stack
-    mod-j
+--     mod-j
-    mod-k
+--     mod-k
-
+-- 
-    mod-h                   resize currently focused window
+--     mod-h                   resize currently focused window
-    mod-l
+--     mod-l
-
+-- 
-    mod-shift-c             kill client
+--     mod-shift-c             kill client
-    mod-shift-q             exit window manager
+--     mod-shift-q             exit window manager
-    mod-shift-ctrl-q        restart window manager
+--     mod-shift-ctrl-q        restart window manager
-
+-- 
-    mod-return              move currently focused window into master position
+--     mod-return              move currently focused window into master position
-
+-- 
-    mod-1..9                switch to workspace N
+--     mod-1..9                switch to workspace N
-    mod-shift-1..9          move client to workspace N
+--     mod-shift-1..9          move client to workspace N
-
+-- 
-    mod-w,e,r               switch to physical/Xinerama screen 1, 2 or 3.
+--     mod-w,e,r               switch to physical/Xinerama screen 1, 2 or 3.
-
+-- 
-xmonad places each window into a "workspace." Each workspace can have
+-- xmonad places each window into a "workspace." Each workspace can have
-any number of windows, which you can cycle though with mod-j and mod-k.
+-- any number of windows, which you can cycle though with mod-j and mod-k.
-Windows are either displayed full screen, tiled horizontally, or tiled
+-- Windows are either displayed full screen, tiled horizontally, or tiled
-vertically. You can toggle the layout mode with mod-space, which will
+-- vertically. You can toggle the layout mode with mod-space, which will
-cycle through the available modes.
+-- cycle through the available modes.
-
+-- 
-You can switch to workspace N with mod-N. For example, to switch to
+-- You can switch to workspace N with mod-N. For example, to switch to
-workspace 5, you would press mod-5. Similarly, you can move the current
+-- workspace 5, you would press mod-5. Similarly, you can move the current
-window to another workspace with mod-shift-N.
+-- window to another workspace with mod-shift-N.
-
+-- 
-When running with multiple monitors (Xinerama), each screen has exactly
+-- When running with multiple monitors (Xinerama), each screen has exactly
-1 workspace visible. When xmonad starts, workspace 1 is on screen 1,
+-- 1 workspace visible. When xmonad starts, workspace 1 is on screen 1,
-workspace 2 is on screen 2, etc. If you switch to a workspace which is
+-- workspace 2 is on screen 2, etc. If you switch to a workspace which is
-currently visible on another screen, xmonad simply switches focus to
+-- currently visible on another screen, xmonad simply switches focus to
-that screen. If you switch to a workspace which is *not* visible, xmonad
+-- that screen. If you switch to a workspace which is *not* visible, xmonad
-replaces the workspace on the *current* screen with the workspace you
+-- replaces the workspace on the *current* screen with the workspace you
-selected.
+-- selected.
-
+-- 
-For example, if you have the following configuration:
+-- For example, if you have the following configuration:
-
+-- 
-Screen 1: Workspace 2
+-- Screen 1: Workspace 2
-Screen 2: Workspace 5 (current workspace)
+-- Screen 2: Workspace 5 (current workspace)
-
+-- 
-and you wanted to view workspace 7 on screen 1, you would press:
+-- and you wanted to view workspace 7 on screen 1, you would press:
-
+-- 
-mod-2 (to select workspace 2, and make screen 1 the current screen)
+-- mod-2 (to select workspace 2, and make screen 1 the current screen)
-mod-7 (to select workspace 7)
+-- mod-7 (to select workspace 7)
-
+-- 
-Since switching to the workspace currently visible on a given screen is
+-- Since switching to the workspace currently visible on a given screen is
-such a common operation, shortcuts are provided: mod-{w,e,r} switch to
+-- such a common operation, shortcuts are provided: mod-{w,e,r} switch to
-the workspace currently visible on screens 1, 2, and 3 respectively.
+-- the workspace currently visible on screens 1, 2, and 3 respectively.
-Likewise, shift-mod-{w,e,r} moves the current window to the workspace on
+-- Likewise, shift-mod-{w,e,r} moves the current window to the workspace on
-that screen.  Using these keys, the above example would become mod-w
+-- that screen.  Using these keys, the above example would become mod-w
-mod-7.
+-- mod-7.
-
+-- 
--}
 
 import Data.Ratio
 import Data.Bits
@@ -129,7 +128,7 @@ keys = M.fromList $
 
     ] ++
     -- Keybindings to get to each workspace:
-    [((m .|. modMask, xK_0 + fromIntegral i), f i)
+    [((m .|. modMask, xK_0 + fromIntegral i), f (fromIntegral (pred i))) -- index from 0.
         | i <- [1 .. workspaces]
         , (f, m) <- [(view, 0), (tag, shiftMask)]]
 

Operations.hs

@@ -29,7 +29,7 @@ refresh = do
            ,display   = d ,layoutDescs = fls  ,defaultLayoutDesc = dfltfl } <- get
 
     flip mapM_ (M.assocs (W.screen2ws ws)) $ \(scn, n) -> do
-        let sc = xinesc !! scn
+        let sc =  genericIndex xinesc scn -- temporary coercion!
             fl = M.findWithDefault dfltfl n fls
         mapM_ (\(w, rect) -> io $ moveWindowInside d w rect) $
             case layoutType fl of
@@ -214,20 +214,19 @@ kill = withDisplay $ \d -> do
                     sendEvent d w False noEventMask ev
             else io (killClient d w) >> return ()
 
--- | tag. Move a window to a new workspace
+-- | tag. Move a window to a new workspace, 0 indexed.
-tag :: Int -> X ()
+tag :: W.WorkspaceId -> X ()
-tag o = do
+tag n = do
     ws <- gets workspace
-    let m = W.current ws
+    let m = W.current ws -- :: WorkspaceId
     when (n /= m) $
         whenJust (W.peek ws) $ \w -> do
             hide w
             windows $ W.shift n
-    where n = o-1
 
--- | view. Change the current workspace to workspce at offset 'n-1'.
+-- | view. Change the current workspace to workspce at offset n (0 indexed).
-view :: Int -> X ()
+view :: W.WorkspaceId -> X ()
-view o = do
+view n = do
     ws <- gets workspace
     let m = W.current ws
     windows $ W.view n
@@ -236,11 +235,10 @@ view o = do
     -- in case we're switching to an empty workspace.
     when (m `notElem` (W.visibleWorkspaces ws')) (mapM_ hide (W.index m ws))
     setTopFocus
-    where n = o-1
 
 -- | 'screenWorkspace sc' returns the workspace number viewed by 'sc'.
-screenWorkspace :: Int -> X Int
+screenWorkspace :: W.ScreenId -> X W.WorkspaceId
-screenWorkspace sc = fmap (succ . fromMaybe 0 . W.workspace sc) (gets workspace)
+screenWorkspace sc = fmap (fromMaybe 0 . W.workspace sc) (gets workspace)
 
 -- | True if window is under management by us
 isClient :: Window -> X Bool

StackSet.hs

@@ -22,7 +22,7 @@
 module StackSet where
 
 import Data.Maybe
-import qualified Data.List     as L (delete)
+import qualified Data.List     as L (delete,genericLength)
 import qualified Data.Map      as M
 
 ------------------------------------------------------------------------
@@ -35,14 +35,20 @@ import qualified Data.Map      as M
 -- | The StackSet data structure. A table of stacks, with a current pointer
 data StackSet a =
     StackSet
-        { current  :: !Int              -- ^ the currently visible stack
+        { current  :: !WorkspaceId                   -- ^ the currently visible stack
-        , ws2screen:: !(M.Map Int Int)  -- ^ workspace -> screen map
+        , screen2ws:: !(M.Map ScreenId WorkspaceId)  -- ^ screen -> workspace
-        , screen2ws:: !(M.Map Int Int)  -- ^ screen -> workspace
+        , ws2screen:: !(M.Map WorkspaceId ScreenId)  -- ^ workspace -> screen map
-        , stacks   :: !(M.Map Int [a])  -- ^ the separate stacks
+        , stacks   :: !(M.Map WorkspaceId [a])       -- ^ the separate stacks
-        , focus    :: !(M.Map Int a)    -- ^ the window focused in each stack
+        , focus    :: !(M.Map WorkspaceId a)         -- ^ the window focused in each stack
-        , cache    :: !(M.Map a Int)    -- ^ a cache of windows back to their stacks
+        , cache    :: !(M.Map a WorkspaceId)         -- ^ a cache of windows back to their stacks
         } deriving Eq
 
+-- | Physical screen indicies
+newtype ScreenId    = S Int deriving (Eq,Ord,Show,Enum,Num,Integral,Real)
+
+-- | Virtual workspace indicies
+newtype WorkspaceId = W Int deriving (Eq,Ord,Show,Enum,Num,Integral,Real)
+
 instance Show a => Show (StackSet a) where
     showsPrec p s r = showsPrec p (show . toList $ s) r
 
@@ -57,19 +63,23 @@ instance Show a => Show (StackSet a) where
 -- screens. (also indexed from 0) The 0-indexed stack will be current.
 empty :: Int -> Int -> StackSet a
 empty n m = StackSet { current   = 0
-                     , ws2screen = wsScreenAssn
+                     , screen2ws = wsScrs2Works
-                     , screen2ws = wsScreenAssn
+
-                     , stacks    = M.fromList (zip [0..n-1] (repeat []))
+                     , ws2screen = wsWorks2Scrs
+                     , stacks    = M.fromList (zip [0..W n-1] (repeat []))
                      , focus     = M.empty
                      , cache     = M.empty }
-    where wsScreenAssn = M.fromList $ map (\x -> (x,x)) [0..m-1]
+
+    where (scrs,wrks)  = unzip $ map (\x -> (S x, W x)) [0..m-1]
+          wsScrs2Works = M.fromList (zip scrs wrks)
+          wsWorks2Scrs = M.fromList (zip wrks scrs)
 
 -- | /O(log w)/. True if x is somewhere in the StackSet
 member :: Ord a => a -> StackSet a -> Bool
 member a w = M.member a (cache w)
 
--- | /O(log n)/. Looks up the stack that x is in, if it is in the StackSet
+-- | /O(log n)/. Looks up the workspace that x is in, if it is in the StackSet
-lookup :: (Monad m, Ord a) => a -> StackSet a -> m Int
+lookup :: (Monad m, Ord a) => a -> StackSet a -> m WorkspaceId
 lookup x w = M.lookup x (cache w)
 
 -- | /O(n)/. Number of stacks
@@ -80,10 +90,11 @@ size = M.size . stacks
 
 -- | fromList. Build a new StackSet from a list of list of elements
 -- If there are duplicates in the list, the last occurence wins.
-fromList :: Ord a => (Int,Int,[[a]]) -> StackSet a
+-- FIXME: This always makes a StackSet with 1 screen.
-fromList (_,_,[]) = error "Cannot build a StackSet from an empty list"
+fromList :: Ord a => (Int,[[a]]) -> StackSet a
+fromList (_,[]) = error "Cannot build a StackSet from an empty list"
 
-fromList (n,m,xs) | n < 0 || n >= length xs
+fromList (n,xs) | n < 0 || n >= length xs
                 = error $ "Cursor index is out of range: " ++ show (n, length xs)
                   | m < 1 || m >  length xs
                 = error $ "Can't have more screens than workspaces: " ++ show (m, length xs)
@@ -93,8 +104,8 @@ fromList (o,m,xs) = view o $ foldr (\(i,ys) s ->
                                       (empty (length xs) m) (zip [0..] xs)
 
 -- | toList. Flatten a stackset to a list of lists
-toList  :: StackSet a -> (Int,Int,[[a]])
+toList  :: StackSet a -> (Int,[[a]])
-toList x = (current x, M.size $ screen2ws x, map snd $ M.toList (stacks x))
+toList x = (current x, map snd $ M.toList (stacks x))
 
 -- | Push. Insert an element onto the top of the current stack.
 -- If the element is already in the current stack, it is moved to the top.
@@ -110,21 +121,23 @@ peek w = peekStack (current w) w
 
 -- | /O(log s)/. Extract the element on the top of the given stack. If no such
 -- element exists, Nothing is returned.
-peekStack :: Int -> StackSet a -> Maybe a
+peekStack :: WorkspaceId -> StackSet a -> Maybe a
 peekStack n w = M.lookup n (focus w)
 
 -- | /O(log s)/. Index. Extract the stack at index 'n'.
 -- If the index is invalid, an exception is thrown.
-index :: Int -> StackSet a -> [a]
+index :: WorkspaceId -> StackSet a -> [a]
 index k w = fromJust (M.lookup k (stacks w))
 
--- | view. Set the stack specified by the Int argument as being visible and the
+-- | view. Set the stack specified by the argument as being visible and the
 -- current StackSet. If the stack wasn't previously visible, it will become
 -- visible on the current screen. If the index is out of range an exception is
 -- thrown.
-view :: Int -> StackSet a -> StackSet a
+view :: WorkspaceId -> StackSet a -> StackSet a
-view n w | n >= 0 && n < M.size (stacks w) = if M.member n (ws2screen w)
+-- view n w | n >= 0 && n < fromIntegral (M.size (stacks w)) -- coerce
-                                                 then w { current = n }
+
+view n w | M.member n (stacks w)
+         = if M.member n (ws2screen w) then w { current = n }
                                        else tweak (fromJust $ screen (current w) w)
          | otherwise = error $ "view: index out of bounds: " ++ show n
   where
@@ -134,15 +147,15 @@ view n w | n >= 0 && n < M.size (stacks w) = if M.member n (ws2screen w)
                  }
 
 -- | That screen that workspace 'n' is visible on, if any.
-screen :: Int -> StackSet a -> Maybe Int
+screen :: WorkspaceId -> StackSet a -> Maybe ScreenId
 screen n w = M.lookup n (ws2screen w)
 
 -- | The workspace visible on screen 'sc'. Nothing if screen is out of bounds.
-workspace :: Int -> StackSet a -> Maybe Int
+workspace :: ScreenId -> StackSet a -> Maybe WorkspaceId
 workspace sc w = M.lookup sc (screen2ws w)
 
 -- | A list of the currently visible workspaces.
-visibleWorkspaces :: StackSet a -> [Int]
+visibleWorkspaces :: StackSet a -> [WorkspaceId]
 visibleWorkspaces = M.keys . ws2screen
 
 --
@@ -168,7 +181,7 @@ rotate o w = maybe w id $ do
 -- the top of stack 'n'. If the stack to move to is not valid, and
 -- exception is thrown.
 --
-shift :: Ord a => Int -> StackSet a -> StackSet a
+shift :: Ord a => WorkspaceId -> StackSet a -> StackSet a
 shift n w = maybe w (\k -> insert k n (delete k w)) (peek w)
 
 -- | /O(log n)/. Insert an element onto the top of stack 'n'.
@@ -176,7 +189,7 @@ shift n w = maybe w (\k -> insert k n (delete k w)) (peek w)
 -- If the element exists on another stack, it is removed from that stack.
 -- If the index is wrong an exception is thrown.
 --
-insert :: Ord a => a -> Int -> StackSet a -> StackSet a
+insert :: Ord a => a -> WorkspaceId -> StackSet a -> StackSet a
 insert k n old = new { cache  = M.insert k n (cache new)
                      , stacks = M.adjust (k:) n (stacks new)
                      , focus  = M.insert n k (focus new) }

XMonad.hs

@@ -20,7 +20,7 @@ module XMonad (
     spawn, trace, whenJust, rot
   ) where
 
-import StackSet (StackSet)
+import StackSet (StackSet,WorkspaceId)
 
 import Control.Monad.State
 import System.IO
@@ -43,7 +43,7 @@ data XState = XState
     , dimensions        :: !(Int,Int)              -- ^ dimensions of the screen, used for hiding windows
     , workspace         :: !WorkSpace              -- ^ workspace list
     , defaultLayoutDesc :: !LayoutDesc             -- ^ default layout
-    , layoutDescs       :: !(M.Map Int LayoutDesc) -- ^ mapping of workspaces to descriptions of their layouts
+    , layoutDescs       :: !(M.Map WorkspaceId LayoutDesc) -- ^ mapping of workspaces to descriptions of their layouts
     }
 
 type WorkSpace = StackSet Window
@@ -60,9 +60,6 @@ data LayoutDesc = LayoutDesc { layoutType   :: !Layout
                              , tileFraction :: !Rational
                              }
 
-
-
-
 -- | The X monad, a StateT transformer over IO encapsulating the window
 -- manager state
 newtype X a = X (StateT XState IO a)