2 files changed, 11 insertions, 0 deletions
diff --git a/Trammel.hs b/Trammel.hs
index bd3cd32..d83b846 100644
--- a/Trammel.hs
+++ b/Trammel.hs
@@ -24,6 +24,14 @@ data Trammel a
   deriving (Eq, Show)
 
 
+instance Functor Trammel where
+    fmap f = \case
+        Append t1 t2 -> Append (fmap f t1) (fmap f t2)
+        Plain s -> Plain (f s)
+        SGR pm t -> SGR pm (fmap f t)
+        Empty -> Empty
+
+
 instance Monoid (Trammel a) where
     mappend = Append
     mempty = Empty
diff --git a/test4.hs b/test4.hs
index b9990a0..d9a2e74 100644
--- a/test4.hs
+++ b/test4.hs
@@ -124,6 +124,7 @@ redraw :: State -> IO ()
 redraw _q@State{..} = do
 
     let image =
+            map (fmap $ fmap $ sub '\t' ' ') $
             map (trammelTake screenWidth . trammelDrop xoffset) $
             take screenHeight $
             headBuffer ++ drop yoffset treeBuffer
@@ -135,6 +136,8 @@ redraw _q@State{..} = do
           putStr $ pp $ "\ESC[H" <> first <> mconcat (map ("\n"<>) rest)
       _ ->
           return ()
+  where
+    sub x x' c = if c == x then x' else c