diff --git a/Control/Monad/Trans/Adjoint.hs b/Control/Monad/Trans/Adjoint.hs
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--- /dev/null
+++ b/Control/Monad/Trans/Adjoint.hs
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+{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies #-}
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Adjoint
+-- Copyright   :  (C) 2011 Edward Kmett
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  Edward Kmett <ekmett@gmail.com>
+-- Stability   :  provisional
+-- Portability :  MPTCs, fundeps
+--
+----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Adjoint
+  ( Adjoint
+  , runAdjoint
+  , adjoint
+  , AdjointT(..)
+  ) where
+
+import Prelude hiding (sequence)
+import Control.Applicative
+import Control.Monad (ap, liftM)
+import Control.Monad.Trans.Class
+import Data.Traversable
+import Data.Functor.Adjunction
+import Data.Functor.Identity
+
+type Adjoint f g = AdjointT f g Identity
+
+newtype AdjointT f g m a = AdjointT { runAdjointT :: g (m (f a)) }
+
+adjoint :: Functor g => g (f a) -> Adjoint f g a
+adjoint = AdjointT . fmap Identity
+
+runAdjoint :: Functor g => Adjoint f g a -> g (f a)
+runAdjoint = fmap runIdentity . runAdjointT
+
+instance (Adjunction f g, Monad m) => Functor (AdjointT f g m) where
+  fmap f (AdjointT g) = AdjointT $ fmap (liftM (fmap f)) g
+  b <$ (AdjointT g) = AdjointT $ fmap (liftM (b <$)) g
+  
+instance (Adjunction f g, Monad m) => Applicative (AdjointT f g m) where
+  pure = AdjointT . leftAdjunct return
+  (<*>) = ap
+
+instance (Adjunction f g, Monad m) => Monad (AdjointT f g m) where
+  return = AdjointT . leftAdjunct return
+  AdjointT m >>= f = AdjointT $ fmap (>>= rightAdjunct (runAdjointT . f)) m
+    
+-- | Exploiting this instance requires that we have the missing Traversables for Identity, (,)e and IdentityT
+instance (Adjunction f g, Traversable f) => MonadTrans (AdjointT f g) where
+  lift = AdjointT . fmap sequence . unit
diff --git a/Data/Functor/Adjunction.hs b/Data/Functor/Adjunction.hs
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--- /dev/null
+++ b/Data/Functor/Adjunction.hs
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+{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, UndecidableInstances #-}
+module Data.Functor.Adjunction 
+  ( Adjunction(..)
+  ) where
+
+import Control.Monad.Instances ()
+import Control.Monad.Trans.Identity
+import Data.Functor.Identity
+
+-- > rightAdjunct unit = id
+-- > leftAdjunct counit = id 
+class (Functor f, Functor g) => Adjunction f g | f -> g, g -> f where
+  unit :: a -> g (f a)
+  counit :: f (g a) -> a
+  leftAdjunct :: (f a -> b) -> a -> g b
+  rightAdjunct :: (a -> g b) -> f a -> b
+  
+  unit = leftAdjunct id
+  counit = rightAdjunct id
+  leftAdjunct f = fmap f . unit
+  rightAdjunct f = counit . fmap f
+
+instance Adjunction ((,)e) ((->)e) where
+  leftAdjunct f a e = f (e, a)
+  rightAdjunct f ~(e, a) = f a e
+
+instance Adjunction Identity Identity where
+  leftAdjunct f = Identity . f . Identity
+  rightAdjunct f = runIdentity . f . runIdentity
+
+instance Adjunction f g => Adjunction (IdentityT f) (IdentityT g) where
+  unit = IdentityT . fmap IdentityT . unit
+  counit = counit . fmap runIdentityT . runIdentityT
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright 2011 Edward Kmett
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+3. Neither the name of the author nor the names of his contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
diff --git a/Setup.lhs b/Setup.lhs
new file mode 100644
--- /dev/null
+++ b/Setup.lhs
@@ -0,0 +1,7 @@
+#!/usr/bin/runhaskell
+> module Main (main) where
+
+> import Distribution.Simple
+
+> main :: IO ()
+> main = defaultMain
diff --git a/adjunctions.cabal b/adjunctions.cabal
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--- /dev/null
+++ b/adjunctions.cabal
@@ -0,0 +1,29 @@
+name:          adjunctions
+category:      Data Structures, Adjunctions
+version:       0.1
+license:       BSD3
+cabal-version: >= 1.6
+license-file:  LICENSE
+author:        Edward A. Kmett
+maintainer:    Edward A. Kmett <ekmett@gmail.com>
+stability:     provisional
+homepage:      http://github.com/ekmett/adjunctions/
+copyright:     Copyright (C) 2011 Edward A. Kmett
+synopsis:      Adjunctions
+description:   Adjunctions
+build-type:    Simple
+
+source-repository head
+  type: git
+  location: git://github.com/ekmett/adjunctions.git
+
+library
+  build-depends: 
+    base >= 4 && < 4.4,
+    transformers >= 0.2.0 && < 0.3
+
+  exposed-modules:
+    Control.Monad.Trans.Adjoint
+    Data.Functor.Adjunction
+
+  ghc-options: -Wall