diff --git a/data-ref.cabal b/data-ref.cabal
--- a/data-ref.cabal
+++ b/data-ref.cabal
@@ -1,5 +1,5 @@
 Name:             data-ref
-Version:          0.0.1.2
+Version:          0.0.2
 License:          BSD3
 License-File:     LICENSE
 Author:           Henning Thielemann <haskell@henning-thielemann.de>
@@ -27,11 +27,12 @@
 Source-Repository this
   type:     darcs
   location: http://hub.darcs.net/thielema/data-ref/
-  tag:      0.0.1.2
+  tag:      0.0.2
 
 Library
   Build-Depends:
     transformers >=0.4 && <0.6,
+    data-accessor >=0.2.2 && <0.3,
     stm >=2.2 && <2.6,
     base >=2 && <5
 
diff --git a/src/Data/Ref.hs b/src/Data/Ref.hs
--- a/src/Data/Ref.hs
+++ b/src/Data/Ref.hs
@@ -1,4 +1,4 @@
-{-
+{- |
 Following an idea by Dominique Devriese:
 <http://www.haskell.org/pipermail/libraries/2013-June/020185.html>
 -}
@@ -34,6 +34,8 @@
 import qualified Control.Monad.Trans.Maybe as MM
 import qualified Control.Monad.Trans.Reader as MR
 import qualified Control.Monad.Trans.Identity as MI
+
+import qualified Data.Accessor.Basic as Accessor
 import Data.Monoid (Monoid)
 
 import Prelude hiding (read)
@@ -44,6 +46,12 @@
 modify :: C m => T m a -> (a -> a) -> m ()
 modify ref f = write ref . f =<< read ref
 
+focus :: C m => Accessor.T a b -> T m a -> T m b
+focus acc ref =
+   Cons
+      (modify ref . Accessor.set acc)
+      (liftM (Accessor.get acc) $ read ref)
+
 newCons :: C m =>
    (a -> m ref) -> (ref -> a -> m ()) -> (ref -> m a) ->
    a -> m (T m a)
@@ -92,3 +100,5 @@
 instance (Monoid w, C m) => C (MWL.WriterT w m) where new = newLifted
 instance (Monoid w, C m) => C (MRWSS.RWST r w s m) where new = newLifted
 instance (Monoid w, C m) => C (MRWSL.RWST r w s m) where new = newLifted
+
+-- ToDo: another interesting instance would be Wrapper (StateT Vault)