diff --git a/Numeric/AD/Internal.hs b/Numeric/AD/Internal.hs
--- a/Numeric/AD/Internal.hs
+++ b/Numeric/AD/Internal.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE Rank2Types, GeneralizedNewtypeDeriving, TemplateHaskell, FlexibleContexts, FlexibleInstances, MultiParamTypeClasses, DeriveFunctor, DeriveFoldable, DeriveTraversable #-}
-{-# OPTIONS_HADDOCK hide, prune #-}
+-- {-# OPTIONS_HADDOCK hide, prune #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Numeric.AD.Internal
@@ -32,9 +32,13 @@
 import Data.Traversable (Traversable, mapAccumL)
 import Data.Foldable (Foldable, toList)
 
+-- | A scalar-to-scalar automatically-differentiable function.
 type UU a = forall s. Mode s => AD s a -> AD s a
+-- | A scalar-to-non-scalar automatically-differentiable function.
 type UF f a = forall s. Mode s => AD s a -> f (AD s a)
+-- | A non-scalar-to-scalar automatically-differentiable function.
 type FU f a = forall s. Mode s => f (AD s a) -> AD s a
+-- | A non-scalar-to-non-scalar automatically-differentiable function.
 type FF f g a = forall s. Mode s => f (AD s a) -> g (AD s a)
 
 on :: (a -> a -> b) -> (c -> a) -> c -> c -> b
diff --git a/Numeric/AD/Internal/Classes.hs b/Numeric/AD/Internal/Classes.hs
--- a/Numeric/AD/Internal/Classes.hs
+++ b/Numeric/AD/Internal/Classes.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE Rank2Types, TypeFamilies, FlexibleInstances, MultiParamTypeClasses, FlexibleContexts, FunctionalDependencies, UndecidableInstances, GeneralizedNewtypeDeriving, TemplateHaskell #-}
-{-# OPTIONS_HADDOCK hide #-}
+-- {-# OPTIONS_HADDOCK hide #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Numeric.AD.Internal.Classes
diff --git a/Numeric/AD/Internal/Comonad.hs b/Numeric/AD/Internal/Comonad.hs
new file mode 100644
--- /dev/null
+++ b/Numeric/AD/Internal/Comonad.hs
@@ -0,0 +1,29 @@
+{-# LANGUAGE TypeOperators, TemplateHaskell, ScopedTypeVariables #-}
+-- {-# OPTIONS_HADDOCK hide #-}
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Numeric.AD.Internal.Comonad
+-- Copyright   :  (c) Edward Kmett 2010
+-- License     :  BSD3
+-- Maintainer  :  ekmett@gmail.com
+-- Stability   :  experimental
+-- Portability :  GHC only
+--
+-----------------------------------------------------------------------------
+
+-- TODO: separate a \"comonads\" package from \"category-extras\"
+
+module Numeric.AD.Internal.Comonad
+    ( Copointed(..)
+    , Comonad(..)
+    ) where
+
+class Functor f => Copointed f where
+    extract :: f a -> a
+
+class Copointed f => Comonad f where
+    duplicate :: f a -> f (f a)
+    extend :: (f a -> b) -> f a -> f b
+
+    duplicate = extend id
+    extend f = fmap f . duplicate
diff --git a/Numeric/AD/Internal/Composition.hs b/Numeric/AD/Internal/Composition.hs
--- a/Numeric/AD/Internal/Composition.hs
+++ b/Numeric/AD/Internal/Composition.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE Rank2Types, TypeFamilies, MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, FlexibleContexts, TemplateHaskell, UndecidableInstances, TypeOperators #-}
-{-# OPTIONS_HADDOCK hide, prune #-}
+-- {-# OPTIONS_HADDOCK hide, prune #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Numeric.AD.Internal.Composition
diff --git a/Numeric/AD/Internal/Forward.hs b/Numeric/AD/Internal/Forward.hs
--- a/Numeric/AD/Internal/Forward.hs
+++ b/Numeric/AD/Internal/Forward.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE Rank2Types, TypeFamilies, DeriveDataTypeable, TemplateHaskell, UndecidableInstances, BangPatterns #-}
-{-# OPTIONS_HADDOCK hide, prune #-}
+-- {-# OPTIONS_HADDOCK hide, prune #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Numeric.AD.Internal.Forward
diff --git a/Numeric/AD/Internal/Iterated.hs b/Numeric/AD/Internal/Iterated.hs
new file mode 100644
--- /dev/null
+++ b/Numeric/AD/Internal/Iterated.hs
@@ -0,0 +1,141 @@
+{-# LANGUAGE TemplateHaskell, ScopedTypeVariables, DeriveDataTypeable, FlexibleContexts, UndecidableInstances #-}
+-- {-# OPTIONS_HADDOCK hide #-}
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Numeric.AD.Internal.Iterated
+-- Copyright   :  (c) Edward Kmett 2010
+-- License     :  BSD3
+-- Maintainer  :  ekmett@gmail.com
+-- Stability   :  experimental
+-- Portability :  GHC only
+--
+-----------------------------------------------------------------------------
+
+module Numeric.AD.Internal.Iterated
+    ( Iterated(..)
+    , tailI
+    , unfoldI
+    ) where
+
+import Control.Applicative
+import Data.Monoid
+import Data.Foldable
+import Data.Traversable
+-- import Data.Data
+-- import Data.Typeable
+import Numeric.AD.Internal
+import Numeric.AD.Internal.Comonad
+import Language.Haskell.TH
+
+infixl 3 :|
+
+data Iterated f a = a :| f (Iterated f a)
+--    deriving (Data, Typeable)
+
+instance Functor f => Functor (Iterated f) where
+    fmap f (a :| as) = f a :| fmap f <$> as
+
+instance Functor f => Copointed (Iterated f) where
+    extract (a :| _) = a
+
+instance Functor f => Comonad (Iterated f) where
+    duplicate aas@(_ :| as) = aas :| duplicate <$> as
+    extend f aas@(_ :| as) = f aas :| extend f <$> as
+
+instance Foldable f => Foldable (Iterated f) where
+    foldMap f (a :| as) = f a `mappend` foldMap (foldMap f) as
+
+instance Traversable f => Traversable (Iterated f) where
+    traverse f (a :| as) = (:|) <$> f a <*> traverse (traverse f) as
+
+-- tails of the f-branching stream comonad/cofree comonad
+tailI :: (Iterated f a) -> f (Iterated f a)
+tailI (_ :| as) = as
+
+unfoldI :: Functor f => (a -> (b, f a)) -> a -> Iterated f b
+unfoldI f a = h :| unfoldI f <$> t
+    where
+        (h, t) = f a
+
+instance Primal (Iterated f) where
+    primal (a :| _) = a
+
+instance Mode f => Mode (Iterated f) where
+    lift a = as
+        where as = a :| lift as
+    (a :| as) <+> (b :| bs) = (a + b) :| (as <+> bs)
+    a *^ (b :| bs) = (a * b) :| (lift a *^ bs)
+    (a :| as) ^* b = (a * b) :| (as ^* lift b)
+    (a :| as) ^/ b = (a / b) :| (as ^/ lift b)
+
+instance Mode f => Lifted (Iterated f) where
+    showsPrec1 n (a :| _) = showsPrec n a
+    (==!) = (==) `on` primal
+    compare1 = compare `on` primal
+    fromInteger1 a = fromInteger a :| fromInteger1 a
+    (a :| as) +! (b :| bs) = (a + b) :| (as +! bs)
+    (a :| as) -! (b :| bs) = (a - b) :| (as -! bs)
+    (a :| as) *! (b :| bs) = (a * b) :| (as *! bs)
+    negate1 (a :| as) = negate a :| negate1 as
+    abs1 (a :| as) = abs a :| abs1 as
+    signum1 (a :| as) = signum a :| signum1 as
+    (a :| as) /! (b :| bs) = (a / b) :| (as /! bs)
+    recip1 (a :| as) = recip a :| recip1 as
+    fromRational1 n = fromRational n :| fromRational1 n
+    toRational1 = toRational . primal
+    pi1 = pi :| pi1
+    exp1 (a :| as) = exp a :| exp1 as
+    log1 (a :| as) = log a :| log1 as
+    sqrt1 (a :| as) = sqrt a :| sqrt1 as
+    (a :| as) **! (b :| bs) = (a ** b) :| (as **! bs)
+    logBase1 (a :| as) (b :| bs) = logBase a b :| logBase1 as bs
+    sin1 (a :| as) = sin a :| sin1 as
+    cos1 (a :| as) = cos a :| cos1 as
+    tan1 (a :| as) = tan a :| tan1 as
+    asin1 (a :| as) = asin a :| asin1 as
+    acos1 (a :| as) = acos a :| acos1 as
+    atan1 (a :| as) = atan a :| atan1 as
+    sinh1 (a :| as) = sinh a :| sinh1 as
+    cosh1 (a :| as) = cosh a :| cosh1 as
+    tanh1 (a :| as) = tanh a :| tanh1 as
+    asinh1 (a :| as) = asinh a :| asinh1 as
+    acosh1 (a :| as) = acosh a :| acosh1 as
+    atanh1 (a :| as) = atanh a :| atanh1 as
+    properFraction1 (a :| as) = (b, c :| cs)
+        where
+            (b, c) = properFraction a
+            (_ :: Int, cs) = properFraction1 as
+    truncate1 = truncate . primal
+    round1 = round . primal
+    ceiling1 = ceiling . primal
+    floor1  = floor . primal
+    floatRadix1 = floatRadix . primal
+    floatDigits1 = floatDigits . primal
+    floatRange1 = floatRange . primal
+    decodeFloat1 = decodeFloat . primal
+    encodeFloat1 m e = encodeFloat m e :| encodeFloat1 m e
+    exponent1 = exponent . primal
+    significand1 (a :| as) = significand a :| significand1 as
+    scaleFloat1 n (a :| as) = scaleFloat n a :| scaleFloat1 n as
+    isNaN1 = isNaN . primal
+    isInfinite1 = isInfinite . primal
+    isDenormalized1 = isDenormalized . primal
+    isNegativeZero1 = isNegativeZero . primal
+    isIEEE1 = isIEEE . primal
+    atan21 (a :| as) (b :| bs) = atan2 a b :| atan21 as bs
+    succ1 (a :| as) = succ a :| succ1 as
+    pred1 (a :| as) = pred a :| pred1 as
+    toEnum1 n = toEnum n :| toEnum1 n
+    fromEnum1 = fromEnum . primal
+    enumFrom1 = error "TODO"
+    enumFromThen1 = error "TODO"
+    enumFromTo1 = error "TODO"
+    enumFromThenTo1 = error "TODO"
+    minBound1 = minBound :| minBound1
+    maxBound1 = maxBound :| maxBound1
+    -- TODO:
+
+-- instance (Mode f, Foo a) => Foo (Iterated f) ...
+deriveNumeric
+    (classP (mkName "Mode") [varT $ mkName "f"]:)
+    (conT (mkName "Iterated") `appT` varT (mkName "f"))
diff --git a/Numeric/AD/Internal/Reverse.hs b/Numeric/AD/Internal/Reverse.hs
--- a/Numeric/AD/Internal/Reverse.hs
+++ b/Numeric/AD/Internal/Reverse.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE Rank2Types, TypeFamilies, MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, FlexibleContexts, TemplateHaskell, UndecidableInstances #-}
-{-# OPTIONS_HADDOCK hide, prune #-}
+-- {-# OPTIONS_HADDOCK hide, prune #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Numeric.AD.Internal.Reverse
diff --git a/Numeric/AD/Internal/Stream.hs b/Numeric/AD/Internal/Stream.hs
--- a/Numeric/AD/Internal/Stream.hs
+++ b/Numeric/AD/Internal/Stream.hs
@@ -1,5 +1,5 @@
-{-# LANGUAGE TypeOperators, TemplateHaskell, ScopedTypeVariables #-}
-{-# OPTIONS_HADDOCK hide #-}
+{-# LANGUAGE StandaloneDeriving, FlexibleContexts, UndecidableInstances #-}
+-- {-# OPTIONS_HADDOCK hide #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Numeric.AD.Internal.Stream
@@ -9,136 +9,56 @@
 -- Stability   :  experimental
 -- Portability :  GHC only
 --
--- A cofree comonad/f-branching stream  for use in returning towers of gradients. 
---
 -----------------------------------------------------------------------------
 
 module Numeric.AD.Internal.Stream 
-    ( (:>)(..)
-    , Comonad(..)
-    , unfold
-    , tails
+    ( Stream(..)
+    , unfoldS
+    , headS
+    , tailS
     ) where
 
 import Control.Applicative
 import Data.Monoid
 import Data.Foldable
 import Data.Traversable
-import Numeric.AD.Internal
-import Language.Haskell.TH
+-- import Data.Data
+-- import Data.Typeable
+import Numeric.AD.Internal.Comonad
 
-infixl 3 :<, :>
+infixl 3 :<
 
-class Functor f => Comonad f where
-    extract :: (f :> a) -> a
-    duplicate :: (f :> a) -> (f :> (f :> a))
-    extend :: ((f :> a) -> b) -> (f :> a) -> (f :> b)
+data Stream f a = a :< f (Stream f a)
 
-data (f :> a) = a :< f (f :> a)
+deriving instance (Show a, Show (f (Stream f a))) => Show (Stream f a)
 
-instance Functor f => Functor ((:>)f) where
+-- TODO: Data, Typeable
+
+instance Functor f => Functor (Stream f) where
     fmap f (a :< as) = f a :< fmap f <$> as
 
-instance Functor f => Comonad ((:>) f) where
+instance Functor f => Copointed (Stream f) where
     extract (a :< _) = a
+
+instance Functor f => Comonad (Stream f) where
     duplicate aas@(_ :< as) = aas :< duplicate <$> as
     extend f aas@(_ :< as) = f aas :< extend f <$> as
 
-instance Foldable f => Foldable ((:>) f) where
+instance Foldable f => Foldable (Stream f) where
     foldMap f (a :< as) = f a `mappend` foldMap (foldMap f) as
 
-instance Traversable f => Traversable ((:>) f) where
+instance Traversable f => Traversable (Stream f) where
     traverse f (a :< as) = (:<) <$> f a <*> traverse (traverse f) as
 
+headS :: Stream f a -> a
+headS (a :< _) = a
+
 -- tails of the f-branching stream comonad/cofree comonad
-tails :: (f :> a) -> f (f :> a)
-tails (_ :< as) = as
+tailS :: Stream f a -> f (Stream f a)
+tailS (_ :< as) = as
 
-unfold :: Functor f => (a -> (b, f a)) -> a -> (f :> b)
-unfold f a = h :< unfold f <$> t 
+unfoldS :: Functor f => (a -> (b, f a)) -> a -> Stream f b
+unfoldS f a = h :< unfoldS f <$> t 
     where
         (h, t) = f a
 
-instance Primal ((:>) f) where
-    primal (a :< _) = a
-
-instance Mode f => Mode ((:>) f) where
-    lift a = as
-        where as = a :< lift as
-    (a :< as) <+> (b :< bs) = (a + b) :< (as <+> bs)
-    a *^ (b :< bs) = (a * b) :< (lift a *^ bs)
-    (a :< as) ^* b = (a * b) :< (as ^* lift b)
-    (a :< as) ^/ b = (a / b) :< (as ^/ lift b)
-
-instance Mode f => Lifted ((:>) f) where
-    showsPrec1 n (a :< _) = showsPrec n a
-    (==!) = (==) `on` primal
-    compare1 = compare `on` primal
-    fromInteger1 a = fromInteger a :< fromInteger1 a
-    (a :< as) +! (b :< bs) = (a + b) :< (as +! bs)
-    (a :< as) -! (b :< bs) = (a - b) :< (as -! bs)
-    (a :< as) *! (b :< bs) = (a * b) :< (as *! bs)
-    negate1 (a :< as) = negate a :< negate1 as
-    abs1 (a :< as) = abs a :< abs1 as
-    signum1 (a :< as) = signum a :< signum1 as
-    (a :< as) /! (b :< bs) = (a / b) :< (as /! bs)
-    recip1 (a :< as) = recip a :< recip1 as
-    fromRational1 n = fromRational n :< fromRational1 n
-    toRational1 = toRational . primal
-    pi1 = pi :< pi1
-    exp1 (a :< as) = exp a :< exp1 as
-    log1 (a :< as) = log a :< log1 as
-    sqrt1 (a :< as) = sqrt a :< sqrt1 as
-    (a :< as) **! (b :< bs) = (a ** b) :< (as **! bs)
-    logBase1 (a :< as) (b :< bs) = logBase a b :< logBase1 as bs
-    sin1 (a :< as) = sin a :< sin1 as
-    cos1 (a :< as) = cos a :< cos1 as
-    tan1 (a :< as) = tan a :< tan1 as
-    asin1 (a :< as) = asin a :< asin1 as
-    acos1 (a :< as) = acos a :< acos1 as
-    atan1 (a :< as) = atan a :< atan1 as
-    sinh1 (a :< as) = sinh a :< sinh1 as
-    cosh1 (a :< as) = cosh a :< cosh1 as
-    tanh1 (a :< as) = tanh a :< tanh1 as
-    asinh1 (a :< as) = asinh a :< asinh1 as
-    acosh1 (a :< as) = acosh a :< acosh1 as
-    atanh1 (a :< as) = atanh a :< atanh1 as
-    properFraction1 (a :< as) = (b, c :< cs) 
-        where
-            (b, c) = properFraction a
-            (_ :: Int, cs) = properFraction1 as
-    truncate1 = truncate . primal
-    round1 = round . primal
-    ceiling1 = ceiling . primal 
-    floor1  = floor . primal 
-    floatRadix1 = floatRadix . primal
-    floatDigits1 = floatDigits . primal
-    floatRange1 = floatRange . primal
-    decodeFloat1 = decodeFloat . primal
-    encodeFloat1 m e = encodeFloat m e :< encodeFloat1 m e
-    exponent1 = exponent . primal 
-    significand1 (a :< as) = significand a :< significand1 as
-    scaleFloat1 n (a :< as) = scaleFloat n a :< scaleFloat1 n as
-    isNaN1 = isNaN . primal 
-    isInfinite1 = isInfinite . primal
-    isDenormalized1 = isDenormalized . primal 
-    isNegativeZero1 = isNegativeZero . primal 
-    isIEEE1 = isIEEE . primal 
-    atan21 (a :< as) (b :< bs) = atan2 a b :< atan21 as bs
-    succ1 (a :< as) = succ a :< succ1 as
-    pred1 (a :< as) = pred a :< pred1 as
-    toEnum1 n = toEnum n :< toEnum1 n
-    fromEnum1 = fromEnum . primal
-    enumFrom1 = error "TODO"
-    enumFromThen1 = error "TODO"
-    enumFromTo1 = error "TODO"
-    enumFromThenTo1 = error "TODO"
-    minBound1 = minBound :< minBound1
-    maxBound1 = maxBound :< maxBound1
-    -- TODO:
-
-
--- instance (Mode f, Foo a) => Foo ((:>) f) ...
-deriveNumeric 
-    (classP (mkName "Mode") [varT $ mkName "f"]:) 
-    (conT (mkName ":>") `appT` varT (mkName "f")) 
diff --git a/Numeric/AD/Internal/Tensors.hs b/Numeric/AD/Internal/Tensors.hs
new file mode 100644
--- /dev/null
+++ b/Numeric/AD/Internal/Tensors.hs
@@ -0,0 +1,62 @@
+{-# LANGUAGE TypeOperators, TemplateHaskell, ScopedTypeVariables #-}
+-- {-# OPTIONS_HADDOCK hide #-}
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Numeric.AD.Internal.Tensors
+-- Copyright   :  (c) Edward Kmett 2010
+-- License     :  BSD3
+-- Maintainer  :  ekmett@gmail.com
+-- Stability   :  experimental
+-- Portability :  GHC only
+--
+-----------------------------------------------------------------------------
+
+module Numeric.AD.Internal.Tensors
+    ( Tensors(..)
+    , headT
+    , tailT
+    , tensors
+    ) where
+
+import Control.Applicative
+import Data.Foldable
+import Data.Traversable
+import Data.Monoid
+--import Data.Data
+--import Data.Typeable
+import Numeric.AD.Internal.Comonad
+import Numeric.AD.Internal.Stream
+
+infixl 3 :-
+
+data Tensors f a = a :- Tensors f (f a)
+-- TODO: deriving (Data, Typeable)
+
+instance Functor f => Functor (Tensors f) where
+    fmap f (a :- as) = f a :- fmap (fmap f) as
+
+instance Foldable f => Foldable (Tensors f) where
+    foldMap f (a :- as) = f a `mappend` foldMap (foldMap f) as
+
+instance Traversable f => Traversable (Tensors f) where
+    traverse f (a :- as) = (:-) <$> f a <*> traverse (traverse f) as
+
+-- | While we can not be a 'Comonad' without a 'fzip'-like operation, you can use the
+-- comonad for @'Stream' f a@ to manipulate a structure comonadically that you can turn 
+-- into 'Tensors'.
+instance Functor f => Copointed (Tensors f) where
+    extract (a :- _) = a
+
+tailT :: Tensors f a -> Tensors f (f a)
+tailT (_ :- as) = as
+{-# INLINE tailT #-}
+
+headT :: Tensors f a -> a
+headT (a :- _) = a
+{-# INLINE headT #-}
+
+tensors :: Functor f => Stream f a -> Tensors f a
+tensors (a :< as) = a :- distribute (tensors <$> as)
+    where
+        distribute :: Functor f => f (Tensors f a) -> Tensors f (f a)
+        distribute x = (headT <$> x) :- distribute (tailT <$> x)
diff --git a/Numeric/AD/Internal/Tower.hs b/Numeric/AD/Internal/Tower.hs
--- a/Numeric/AD/Internal/Tower.hs
+++ b/Numeric/AD/Internal/Tower.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE Rank2Types, TypeFamilies, FlexibleContexts, UndecidableInstances, TemplateHaskell #-}
-{-# OPTIONS_HADDOCK hide, prune #-}
+-- {-# OPTIONS_HADDOCK hide, prune #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      : Numeric.AD.Tower.Internal
diff --git a/Numeric/AD/Stream.hs b/Numeric/AD/Stream.hs
deleted file mode 100644
--- a/Numeric/AD/Stream.hs
+++ /dev/null
@@ -1,22 +0,0 @@
-{-# LANGUAGE TypeOperators, TemplateHaskell, ScopedTypeVariables #-}
------------------------------------------------------------------------------
--- |
--- Module      :  Numeric.AD.Stream
--- Copyright   :  (c) Edward Kmett 2010
--- License     :  BSD3
--- Maintainer  :  ekmett@gmail.com
--- Stability   :  experimental
--- Portability :  GHC only
---
--- A cofree comonad/f-branching stream  for use in returning towers of gradients. 
---
------------------------------------------------------------------------------
-
-module Numeric.AD.Stream 
-    ( (:>)(..)
-    , Comonad(..)
-    , unfold
-    , tails
-    ) where
-
-import Numeric.AD.Internal.Stream
diff --git a/Numeric/AD/Tensors.hs b/Numeric/AD/Tensors.hs
new file mode 100644
--- /dev/null
+++ b/Numeric/AD/Tensors.hs
@@ -0,0 +1,32 @@
+{-# LANGUAGE TypeOperators, TemplateHaskell, ScopedTypeVariables #-}
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Numeric.AD.Tensors
+-- Copyright   :  (c) Edward Kmett 2010
+-- License     :  BSD3
+-- Maintainer  :  ekmett@gmail.com
+-- Stability   :  experimental
+-- Portability :  GHC only
+--
+-----------------------------------------------------------------------------
+
+module Numeric.AD.Tensors
+    ( 
+    -- * Tensors
+      Tensors(..)
+    , headT
+    , tailT
+    , tensors
+    -- * f-Branching Streams
+    , Stream(..)
+    , headS
+    , tailS
+    , unfoldS
+    -- * Comonads
+    , Copointed(..)
+    , Comonad(..)
+    ) where
+
+import Numeric.AD.Internal.Comonad
+import Numeric.AD.Internal.Stream
+import Numeric.AD.Internal.Tensors
diff --git a/ad.cabal b/ad.cabal
--- a/ad.cabal
+++ b/ad.cabal
@@ -1,5 +1,5 @@
 Name:         ad
-Version:      0.27
+Version:      0.28
 License:      BSD3
 License-File: LICENSE
 Copyright:    (c) Edward Kmett 2010,
@@ -31,14 +31,19 @@
     Numeric.AD.Tower
     Numeric.AD.Directed
     Numeric.AD.Newton
-    Numeric.AD.Stream
+    Numeric.AD.Tensors
+
     Numeric.AD.Internal
     Numeric.AD.Internal.Classes
+    Numeric.AD.Internal.Comonad
+    Numeric.AD.Internal.Stream
+    Numeric.AD.Internal.Tensors
+
     Numeric.AD.Internal.Composition
     Numeric.AD.Internal.Forward
     Numeric.AD.Internal.Reverse
     Numeric.AD.Internal.Tower
-    Numeric.AD.Internal.Stream
+    Numeric.AD.Internal.Iterated
 
 Extra-Source-Files: TODO
 GHC-Options: -Wall