diff --git a/Data/Record/Label.hs b/Data/Record/Label.hs
deleted file mode 100644
--- a/Data/Record/Label.hs
+++ /dev/null
@@ -1,143 +0,0 @@
-{-# LANGUAGE TypeOperators, TypeSynonymInstances, TemplateHaskell #-}
-module Data.Record.Label
-  (
-  -- * Getter, setter and modifier types.
-    Getter
-  , Setter
-  , Modifier
-
-  -- * Label type.
-  , Point
-  , (:->) (Label)
-  , label
-  , get, set, mod
-
-  -- * Bidirectional functor.
-  , (:<->:) (..)
-  , (<->)
-  , Iso (..)
-  , for
-
-  -- * State monadic label operations.
-
-  , getM, setM, modM, (=:)
-
-  -- * Derive labels using Template Haskell.
-  , module Data.Record.Label.TH
-  )
-where
-
-import Prelude hiding ((.), id, mod)
-import Control.Applicative
-import Control.Category
-import Control.Monad.State hiding (get)
-import Data.Record.Label.TH
-
-type Getter   f o   = f -> o
-type Setter   f i   = i -> f -> f
-type Modifier f i o = (o -> i) -> f -> f
-
-data Point f i o = Point
-  { _get :: Getter f o
-  , _set :: Setter f i
-  }
-
-_mod :: Point f i o -> (o -> i) -> f -> f
-_mod l f a = _set l (f (_get l a)) a
-
-newtype (f :-> a) = Label { unLabel :: Point f a a }
-
--- Create a label out of a getter and setter.
-
-label :: Getter f a -> Setter f a -> f :-> a
-label g s = Label (Point g s)
-
--- | Get the getter function from a label.
-
-get :: (f :-> a) -> f -> a
-get = _get . unLabel
-
--- | Get the setter function from a label.
-
-set :: (f :-> a) -> a -> f -> f
-set = _set . unLabel
-
--- | Get the modifier function from a label.
-
-mod :: (f :-> a) -> (a -> a) -> f -> f
-mod = _mod . unLabel
-
-instance Category (:->) where
-  id = Label (Point id const)
-  (Label a) . (Label b) = Label (Point (_get a . _get b) (_mod b . _set a))
-
-instance Functor (Point f i) where
-  fmap f x = Point (f . _get x) (_set x)
-
-instance Applicative (Point f i) where
-  pure a = Point (const a) (const id)
-  a <*> b = Point (\f -> _get a f (_get b f)) (\r -> _set b r . _set a r)
-
--- | This isomorphism type class is like a `Functor' but works in two directions.
-
-class Iso f where
-  iso :: a :<->: b -> f a -> f b
-  iso (Lens a b) = osi (b <-> a)
-  osi :: a :<->: b -> f b -> f a
-  osi (Lens a b) = iso (b <-> a)
-
--- | The lens datatype, a function that works in two directions. To bad there
--- is no convenient way to do application for this.
-
-data a :<->: b = Lens { fw :: a -> b, bw :: b -> a }
-
--- | Constructor for lenses.
-
-infixr 7 <->
-(<->) :: (a -> b) -> (b -> a) -> a :<->: b
-a <-> b = Lens a b
-
-instance Category (:<->:) where
-  id = Lens id id
-  (Lens a b) . (Lens c d) = Lens (a . c) (d . b)
-
-instance Iso ((:->) i) where
-  iso l (Label a) = Label (Point (fw l . _get a) (_set a . bw l))
-
-instance Iso ((:<->:) i) where
-  iso = (.)
-
-dimap :: (o' -> o) -> (i -> i') -> Point f i' o' -> Point f i o
-dimap f g l = Point (f . _get l) (_set l . g)
-
--- | Combine a partial destructor with a label into something easily used in
--- the applicative instance for the hidden `Point' datatype. Internally uses
--- the covariant in getter, contravariant in setter bi-functioral-map function.
--- (Please refer to the example because this function is just not explainable
--- on its own.)
-
-for :: (i -> o) -> (f :-> o) -> Point f i o
-for a b = dimap id a (unLabel b)
-
--- | Get a value out of state pointed to by the specified label.
-
-getM :: MonadState s m => s :-> b -> m b
-getM = gets . get
-
--- | Set a value somewhere in state pointed to by the specified label.
-
-setM :: MonadState s m => s :-> b -> b -> m ()
-setM l = modify . set l
-
--- | Alias for `setM' that reads like an assignment.
-
-infixr 7 =:
-(=:) :: MonadState s m => s :-> b -> b -> m ()
-(=:) = setM
-
--- | Modify a value with a function somewhere in state pointed to by the
--- specified label.
-
-modM :: MonadState s m => s :-> b -> (b -> b) -> m ()
-modM l = modify . mod l
-
diff --git a/Data/Record/Label/TH.hs b/Data/Record/Label/TH.hs
deleted file mode 100644
--- a/Data/Record/Label/TH.hs
+++ /dev/null
@@ -1,35 +0,0 @@
-module Data.Record.Label.TH (mkLabels) where
-
-import Control.Monad
-import Data.Char
-import Language.Haskell.TH.Syntax
-
--- | Derive labels for all the record selector in a datatype.
-mkLabels :: [Name] -> Q [Dec]
-mkLabels = liftM concat . mapM mkLabels1
-
-mkLabels1 :: Name -> Q [Dec]
-mkLabels1 n = do
-    i <- reify n
-    let -- only process data declarations
-        cs' = case i of { TyConI (DataD _ _ _ cs _) -> cs ; _ -> [] }
-        -- we're only interested in labels of record constructors
-        ls' = [ l | RecC _ ls <- cs', l <- ls ]
-    return (map mkLabel1 ls')
-
-mkLabel1 :: VarStrictType -> Dec
-mkLabel1 (name, _, _) =
-    -- Generate a name for the label:
-    -- If the original selector starts with an _, remove it and make the next
-    -- character lowercase.  Otherwise, add 'l', and make the next character
-    -- uppercase.
-    let n = mkName $ case nameBase name of
-                ('_' : c : rest) -> toLower c : rest
-                (f : rest)       -> 'l' : toUpper f : rest
-                _                -> ""
-    in FunD n [Clause [] (NormalB (
-           AppE (AppE (VarE (mkName "label")) (VarE name)) -- getter
-                (LamE [VarP (mkName "b"), VarP (mkName "a")] -- setter
-                      (RecUpdE (VarE (mkName "a")) [(name, VarE (mkName "b"))]))
-                                   )) []]
-
diff --git a/fclabels.cabal b/fclabels.cabal
--- a/fclabels.cabal
+++ b/fclabels.cabal
@@ -1,5 +1,5 @@
 Name:            fclabels
-Version:         0.4.1
+Version:         0.4.2
 Author:          Sebastiaan Visser, Erik Hesselink, Chris Eidhof, Sjoerd Visscher.
 Synopsis:        First class accessor labels.
 
@@ -135,7 +135,8 @@
 Category:        Data
 Build-Type:      Simple
 Cabal-Version:   >= 1.6
+HS-Source-Dirs:  src
 Exposed-Modules: Data.Record.Label
 Other-Modules:   Data.Record.Label.TH
-Build-Depends:   base >= 3 && < 5, template-haskell >= 2.2 && < 2.4, monads-fd ==0.0.*
+Build-Depends:   base >= 3 && < 5, template-haskell >= 2.2 && < 2.5, monads-fd ==0.0.*
 
diff --git a/src/Data/Record/Label.hs b/src/Data/Record/Label.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Record/Label.hs
@@ -0,0 +1,152 @@
+{-# LANGUAGE TypeOperators, TypeSynonymInstances, TemplateHaskell #-}
+module Data.Record.Label
+  (
+  -- * Getter, setter and modifier types.
+    Getter
+  , Setter
+  , Modifier
+
+  -- * Label type.
+  , Point
+  , (:->) (Label)
+  , label
+  , get, set, mod
+
+  , fmapL
+
+  -- * Bidirectional functor.
+  , (:<->:) (..)
+  , (<->)
+  , Iso (..)
+  , lmap
+  , for
+
+  -- * State monadic label operations.
+
+  , getM, setM, modM, (=:)
+
+  -- * Derive labels using Template Haskell.
+  , module Data.Record.Label.TH
+  )
+where
+
+import Prelude hiding ((.), id, mod)
+import Control.Applicative
+import Control.Category
+import Control.Monad.State hiding (get)
+import Data.Record.Label.TH
+
+type Getter   f o   = f -> o
+type Setter   f i   = i -> f -> f
+type Modifier f i o = (o -> i) -> f -> f
+
+data Point f i o = Point
+  { _get :: Getter f o
+  , _set :: Setter f i
+  }
+
+_mod :: Point f i o -> (o -> i) -> f -> f
+_mod l f a = _set l (f (_get l a)) a
+
+newtype (f :-> a) = Label { unLabel :: Point f a a }
+
+-- Create a label out of a getter and setter.
+
+label :: Getter f a -> Setter f a -> f :-> a
+label g s = Label (Point g s)
+
+-- | Get the getter function from a label.
+
+get :: (f :-> a) -> f -> a
+get = _get . unLabel
+
+-- | Get the setter function from a label.
+
+set :: (f :-> a) -> a -> f -> f
+set = _set . unLabel
+
+-- | Get the modifier function from a label.
+
+mod :: (f :-> a) -> (a -> a) -> f -> f
+mod = _mod . unLabel
+
+instance Category (:->) where
+  id = Label (Point id const)
+  (Label a) . (Label b) = Label (Point (_get a . _get b) (_mod b . _set a))
+
+instance Functor (Point f i) where
+  fmap f x = Point (f . _get x) (_set x)
+
+instance Applicative (Point f i) where
+  pure a = Point (const a) (const id)
+  a <*> b = Point (_get a <*> _get b) (\r -> _set b r . _set a r)
+
+fmapL :: Applicative f => (a :-> b) -> f a :-> f b
+fmapL l = label (fmap (get l)) (\x f -> set l <$> x <*> f)
+
+-- | This isomorphism type class is like a `Functor' but works in two directions.
+
+class Iso f where
+  iso :: a :<->: b -> f a -> f b
+  iso (Lens a b) = osi (b <-> a)
+  osi :: a :<->: b -> f b -> f a
+  osi (Lens a b) = iso (b <-> a)
+
+-- | The lens datatype, a function that works in two directions. To bad there
+-- is no convenient way to do application for this.
+
+data a :<->: b = Lens { fw :: a -> b, bw :: b -> a }
+
+-- | Constructor for lenses.
+
+infixr 7 <->
+(<->) :: (a -> b) -> (b -> a) -> a :<->: b
+a <-> b = Lens a b
+
+instance Category (:<->:) where
+  id = Lens id id
+  (Lens a b) . (Lens c d) = Lens (a . c) (d . b)
+
+instance Iso ((:->) i) where
+  iso l (Label a) = Label (Point (fw l . _get a) (_set a . bw l))
+
+instance Iso ((:<->:) i) where
+  iso = (.)
+
+lmap :: Functor f => (a :<->: b) -> f a :<->: f b 
+lmap l = let (Lens a b) = l in fmap a <-> fmap b
+
+dimap :: (o' -> o) -> (i -> i') -> Point f i' o' -> Point f i o
+dimap f g l = Point (f . _get l) (_set l . g)
+
+-- | Combine a partial destructor with a label into something easily used in
+-- the applicative instance for the hidden `Point' datatype. Internally uses
+-- the covariant in getter, contravariant in setter bi-functioral-map function.
+-- (Please refer to the example because this function is just not explainable
+-- on its own.)
+
+for :: (i -> o) -> (f :-> o) -> Point f i o
+for a b = dimap id a (unLabel b)
+
+-- | Get a value out of state pointed to by the specified label.
+
+getM :: MonadState s m => s :-> b -> m b
+getM = gets . get
+
+-- | Set a value somewhere in state pointed to by the specified label.
+
+setM :: MonadState s m => s :-> b -> b -> m ()
+setM l = modify . set l
+
+-- | Alias for `setM' that reads like an assignment.
+
+infixr 7 =:
+(=:) :: MonadState s m => s :-> b -> b -> m ()
+(=:) = setM
+
+-- | Modify a value with a function somewhere in state pointed to by the
+-- specified label.
+
+modM :: MonadState s m => s :-> b -> (b -> b) -> m ()
+modM l = modify . mod l
+
diff --git a/src/Data/Record/Label/TH.hs b/src/Data/Record/Label/TH.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Record/Label/TH.hs
@@ -0,0 +1,38 @@
+module Data.Record.Label.TH (mkLabels) where
+
+import Control.Monad
+import Data.Char
+import Language.Haskell.TH.Syntax
+
+-- | Derive labels for all the record selector in a datatype.
+mkLabels :: [Name] -> Q [Dec]
+mkLabels = liftM concat . mapM mkLabels1
+
+mkLabels1 :: Name -> Q [Dec]
+mkLabels1 n = do
+    i <- reify n
+    let -- only process data and newtype declarations
+        cs' = case i of
+                TyConI (DataD _ _ _ cs _)   -> cs
+                TyConI (NewtypeD _ _ _ c _) -> [c]
+                _ -> []
+        -- we're only interested in labels of record constructors
+        ls' = [ l | RecC _ ls <- cs', l <- ls ]
+    return (map mkLabel1 ls')
+
+mkLabel1 :: VarStrictType -> Dec
+mkLabel1 (name, _, _) =
+    -- Generate a name for the label:
+    -- If the original selector starts with an _, remove it and make the next
+    -- character lowercase.  Otherwise, add 'l', and make the next character
+    -- uppercase.
+    let n = mkName $ case nameBase name of
+                ('_' : c : rest) -> toLower c : rest
+                (f : rest)       -> 'l' : toUpper f : rest
+                _                -> ""
+    in FunD n [Clause [] (NormalB (
+           AppE (AppE (VarE (mkName "label")) (VarE name)) -- getter
+                (LamE [VarP (mkName "b"), VarP (mkName "a")] -- setter
+                      (RecUpdE (VarE (mkName "a")) [(name, VarE (mkName "b"))]))
+                                   )) []]
+