xmonad: add constansts for layout ids

users/modules/window_manager/xmonad_config.hs

@@ -163,9 +163,9 @@ myPolybarLogHook dbus = myLogHook <+> dynamicLogWithPP (polybarHook dbus)
 --
 myLayoutHook = mirrorTiled ||| tiled ||| full
   where
-    full = layout "Full" Full
-    tiled = layout "Tall" baseTiled
-    mirrorTiled = layout "Mirror Tall" $ Mirror baseTiled
+    full = layout fullLayoutId Full
+    tiled = layout tallLayoutId baseTiled
+    mirrorTiled = layout mirrorTallLayoutId $ Mirror baseTiled
 
     layout n l = renamed [Replace n] $ avoidStruts . smartBorders . minimize . boringWindows $ l
 
@@ -177,6 +177,10 @@ myLayoutHook = mirrorTiled ||| tiled ||| full
     gapSpaced g = spacing g . myGaps g
     myGaps gap = gaps [(U, gap), (D, gap), (L, gap), (R, gap)]
 
+fullLayoutId = "Full"
+tallLayoutId = "Tall"
+mirrorTallLayoutId = "Mirror Tall"
+
 ------------------------------------------------------------------------
 -- Startup hook
 
@@ -308,8 +312,8 @@ myKeys conf =
     layout_kb =
       [ -- Rotate through the available layout algorithms
         -- ("M-<Space>", sendMessage NextLayout),
-        ("M-<Space>", cycleThroughLayouts ["Full", "Mirror Tall"]),
-        ("M-<Tab>", cycleThroughLayouts ["Tall", "Mirror Tall"]),
+        ("M-<Space>", cycleThroughLayouts [fullLayoutId, mirrorTallLayoutId]),
+        ("M-<Tab>", cycleThroughLayouts [tallLayoutId, mirrorTallLayoutId]),
         --  Reset the layouts on the current workspace to default
         ("M-S-<Space>", setLayout $ XMonad.layoutHook conf),
         -- Shrink the master area