Sketch of XMonad.Config.Monad

XMonad/Config/Monad.hs

@@ -0,0 +1,49 @@
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+
+-- experimental, not expected to work
+
+{- our goal:
+config = do
+    add layout Full
+    set terminal "urxvt"
+    add keys [blah blah blah]
+-}
+
+{-
+ideas:
+    composability!
+    "only once" features like avoidStruts, ewmhDesktops
+-}
+
+module XMonad.Config.Monad where
+
+import XMonad hiding (terminal, keys)
+import qualified XMonad as X
+import Control.Monad.Writer
+import Data.Monoid
+import Data.Accessor
+import Data.Accessor.Basic hiding (set)
+
+-- Ugly!  To fix this we'll need to change the kind of XConfig.
+newtype LayoutList a = LL [Layout a] deriving Monoid
+
+type W = Dual (Endo (XConfig LayoutList))
+mkW = Dual . Endo
+
+newtype Config a = C (WriterT W IO a)
+    deriving (Functor, Monad, MonadWriter W)
+
+-- references:
+layout = fromSetGet (\x c -> c { layoutHook = x }) layoutHook
+terminal = fromSetGet (\x c -> c { X.terminal = x }) X.terminal
+keys = fromSetGet (\x c -> c { X.keys = x }) X.keys
+
+set :: Accessor (XConfig LayoutList) a -> a -> Config () 
+set r x = tell (mkW $ r ^= x)
+add r x = tell (mkW (r ^: mappend x))
+
+--
+example :: Config ()
+example = do
+    add layout $ LL [Layout $ Full] -- make this better
+    set terminal "urxvt"