add new LayoutHelpers module.

LayoutHelpers.hs

@@ -0,0 +1,62 @@
+-----------------------------------------------------------------------------
+-- |
+-- Module       : XMonadContrib.LayoutHelpers
+-- Copyright    : (c) David Roundy <droundy@darcs.net>
+-- License      : BSD
+--
+-- Maintainer   : David Roundy <droundy@darcs.net>
+-- Stability    : unstable
+-- Portability  : portable
+--
+-- Make layouts respect size hints.
+-----------------------------------------------------------------------------
+
+module XMonadContrib.LayoutHelpers (
+    -- * usage
+    -- $usage
+    DoLayout, ModDo, ModMod, ModLay,
+    layoutModify,
+    l2lModDo,
+    idModMod,
+    ) where
+
+import Graphics.X11.Xlib ( Rectangle )
+import XMonad
+import StackSet ( Stack, integrate )
+
+-- $usage
+-- Use LayoutHelpers to help write easy Layouts.
+
+--type DoLayout a = Rectangle -> Stack a -> X ([(a, Rectangle)], Maybe (Layout a))
+type DoLayout a = Rectangle -> Stack a -> X [(a, Rectangle)]
+type ModifyLayout a = SomeMessage -> X (Maybe (Layout a))
+
+type ModDo a = Rectangle -> Stack a -> [(a, Rectangle)] -> X ([(a, Rectangle)], Maybe (ModLay a))
+type ModMod a = SomeMessage -> X (Maybe (ModLay a))
+
+type ModLay a = Layout a -> Layout a
+
+layoutModify :: ModDo a -> ModMod a -> ModLay a
+layoutModify fdo fmod l = Layout { doLayout = dl, modifyLayout = modl }
+    where dl r s = do --(ws, ml') <- doLayout l r s
+                      ws <- doLayout l r s
+                      (ws', mmod') <- fdo r s ws
+                      --let ml'' = case mmod' of
+                      --           Just mod' -> Just $ mod' $ maybe l id ml'
+                      --           Nothing -> layoutModify fdo mod `fmap` ml'
+                      --return (ws', ml'')
+                      case mmod' of
+                        Just _ -> fail "Sorry, can't yet safely modify layouts in doLayout."
+                        Nothing -> return ws'
+          modl m = do ml' <- modifyLayout l m
+                      mmod' <- fmod m
+                      return $ case mmod' of
+                               Just mod' -> Just $ mod' $ maybe l id ml'
+                               Nothing -> layoutModify fdo fmod `fmap` ml'
+
+l2lModDo :: (Rectangle -> [a] -> [(a,Rectangle)]) -> DoLayout a
+--l2lModDo dl r s = return (dl r $ integrate s, Nothing)
+l2lModDo dl r s = return (dl r $ integrate s)
+
+idModMod :: ModMod a
+idModMod _ = return Nothing