documentation for IndependentScreens

XMonad/Layout/IndependentScreens.hs

@@ -13,7 +13,15 @@
 -- distinguish workspaces associated with each screen.
 -----------------------------------------------------------------------------
 
-module XMonad.Layout.IndependentScreens where
+module XMonad.Layout.IndependentScreens (
+    -- * Usage
+    -- $usage
+    VirtualWorkspace, PhysicalWorkspace,
+    workspaces',
+    withScreens, onCurrentScreen,
+    countScreens,
+    marshall, unmarshall
+) where
 
 -- for the screen stuff
 import Control.Arrow hiding ((|||))
@@ -24,8 +32,40 @@ import Graphics.X11.Xinerama
 import XMonad
 import XMonad.StackSet hiding (workspaces)
 
-type VirtualWorkspace  = String
+-- $usage
-type PhysicalWorkspace = String
+-- You can use this module with the following in your @~\/.xmonad\/xmonad.hs@:
+--
+-- > import XMonad.Layout.IndependentScreens
+--
+-- You can define your workspaces by calling @withScreens@:
+--
+-- > myConfig = defaultConfig { workspaces = withScreens 2 ["web", "email", "irc"] }
+--
+-- This will create \"physical\" workspaces with distinct internal names for
+-- each (screen, virtual workspace) pair.
+--
+-- Then edit any keybindings that use the list of workspaces or refer
+-- to specific workspace names.  In the default configuration, only
+-- the keybindings for changing workspace do this:
+--
+-- > [((m .|. modMask, k), windows $ f i)
+-- >     | (i, k) <- zip (XMonad.workspaces conf) [xK_1 .. xK_9]
+-- >     , (f, m) <- [(W.greedyView, 0), (W.shift, shiftMask)]]
+--
+-- This should change to
+--
+-- > [((m .|. modMask, k), windows $ onCurrentScreen f i)
+-- >     | (i, k) <- zip (workspaces' conf) [xK_1 .. xK_9]
+-- >     , (f, m) <- [(W.greedyView, 0), (W.shift, shiftMask)]]
+--
+-- In particular, the analogue of @XMonad.workspaces@ is
+-- @workspaces'@, and you can use @onCurrentScreen@ to convert functions
+-- of virtual workspaces to functions of physical workspaces, which work
+-- by marshalling the virtual workspace name and the currently focused
+-- screen into a physical workspace name.
+
+type VirtualWorkspace  = WorkspaceId
+type PhysicalWorkspace = WorkspaceId
 
 marshall :: ScreenId -> VirtualWorkspace -> PhysicalWorkspace
 marshall (S sc) vws = show sc ++ '_':vws
@@ -33,14 +73,32 @@ marshall (S sc) vws = show sc ++ '_':vws
 unmarshall :: PhysicalWorkspace -> (ScreenId, VirtualWorkspace)
 unmarshall = ((S . read) *** drop 1) . break (=='_')
 
+-- ^ You shouldn't need to use @marshall@ and @unmarshall@ very much.
+-- They simply convert between the physical and virtual worlds.  For
+-- example, you might want to use them as part of a status bar
+-- configuration.  The function @snd . unmarshall@ would discard the
+-- screen information from an otherwise unsightly workspace name.
+
 workspaces' :: XConfig l -> [VirtualWorkspace]
 workspaces' = nub . map (snd . unmarshall) . workspaces
 
-withScreens :: ScreenId -> [VirtualWorkspace] -> [PhysicalWorkspace]
+withScreens :: ScreenId            -- ^ The number of screens to make workspaces for
+            -> [VirtualWorkspace]  -- ^ The desired virtual workspace names
+            -> [PhysicalWorkspace] -- ^ A list of all internal physical workspace names
 withScreens n vws = [marshall sc pws | pws <- vws, sc <- [0..n-1]]
 
-onScreen :: (VirtualWorkspace -> WindowSet -> a) -> (PhysicalWorkspace -> WindowSet -> a)
+onCurrentScreen :: (VirtualWorkspace -> WindowSet -> a) -> (PhysicalWorkspace -> WindowSet -> a)
-onScreen f vws = screen . current >>= f . flip marshall vws
+onCurrentScreen f vws = screen . current >>= f . flip marshall vws
 
+-- | In case you don't know statically how many screens there will be, you can call this in main before starting xmonad.  For example, part of my config reads
+--
+-- > main = do
+-- >   nScreens <- countScreens
+-- >   xmonad $ defaultConfig {
+-- >     ...
+-- >     workspaces = withScreens nScreens (workspaces defaultConfig),
+-- >     ...
+-- >     }
+--
 countScreens :: (MonadIO m, Integral i) => m i
 countScreens = liftM genericLength . liftIO $ openDisplay "" >>= getScreenInfo