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-rw-r--r--XMonad.hs15
1 files changed, 7 insertions, 8 deletions
diff --git a/XMonad.hs b/XMonad.hs
index 5a39661..248a578 100644
--- a/XMonad.hs
+++ b/XMonad.hs
@@ -28,6 +28,7 @@ import Prelude hiding ( catch )
import Control.Exception (catch, throw, Exception(ExitException))
import Control.Monad.State
import Control.Monad.Reader
+import Control.Arrow (first)
import System.IO
import System.Posix.Process (executeFile, forkProcess, getProcessStatus, createSession)
import System.Exit
@@ -128,25 +129,23 @@ atom_WM_DELETE_WINDOW = getAtom "WM_DELETE_WINDOW"
atom_WM_STATE = getAtom "WM_STATE"
------------------------------------------------------------------------
--- | LayoutClass handling
+-- | LayoutClass handling. See particular instances in Operations.hs
--- | And existential class that can hold any object that is in
--- the LayoutClass.
+-- | An existential type that can hold any object that is in the LayoutClass.
data Layout a = forall l. LayoutClass l a => Layout (l a)
-- | This class defines a set of layout types (held in Layout
--- objects) that are used when trying to read an existential
--- Layout.
+-- objects) that are used when trying to read an existentially wrapped Layout.
class ReadableLayout a where
defaults :: [Layout a]
-- | The different layout modes
+--
-- 'doLayout': given a Rectangle and a Stack, layout the stack elements
-- inside the given Rectangle. If an element is not given a Rectangle
-- by 'doLayout', then it is not shown on screen. Windows are restacked
-- according to the order they are returned by 'doLayout'.
--
-
class (Show (layout a), Read (layout a)) => LayoutClass layout a where
-- | Given a Rectangle in which to place the windows, and a Stack of
@@ -185,12 +184,12 @@ instance ReadableLayout a => Read (Layout a) where
readsPrec _ s = take 1 $ concatMap rl defaults
-- We take the first parse only, because multiple matches
-- indicate a bad parse.
- where rl (Layout x) = map (\(l,s') -> (Layout l,s')) $ rl' x
+ where rl (Layout x) = map (first Layout) $ rl' x
rl' :: LayoutClass l a => l a -> [(l a,String)]
rl' _ = reads s
instance ReadableLayout a => LayoutClass Layout a where
- doLayout (Layout l) r s = fmap (fmap $ fmap Layout) $ doLayout l r s
+ doLayout (Layout l) r s = fmap (fmap Layout) `liftM` doLayout l r s
handleMessage (Layout l) = fmap (fmap Layout) . handleMessage l
description (Layout l) = description l