vanadium/xmonad: show nmaster count in description

nix/configurations/vanadium/home/xmonad/lib/Leanamonad/Layout/ReflectMsg.hs

@@ -0,0 +1,29 @@
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+
+module Leanamonad.Layout.ReflectMsg where
+
+import XMonad (
+  Resize (Expand, Shrink),
+  SomeMessage (SomeMessage),
+  fromMessage,
+ )
+
+import XMonad.Layout.LayoutModifier (
+  LayoutModifier (handleMess, handleMessOrMaybeModifyIt),
+  ModifiedLayout (ModifiedLayout),
+ )
+
+data ReflectMsg a = ReflectMsg deriving (Show, Read)
+
+reflectMsg :: l a -> ModifiedLayout ReflectMsg l a
+reflectMsg = ModifiedLayout ReflectMsg
+
+instance LayoutModifier ReflectMsg a where
+  handleMessOrMaybeModifyIt m mess
+    | Just Shrink <- fromMessage mess = return . Just . Right $ SomeMessage Expand
+    | Just Expand <- fromMessage mess = return . Just . Right $ SomeMessage Shrink
+    -- Handle the rest by passing it on
+    | otherwise = do
+        mm <- handleMess m mess
+        return (Left <$> mm)