diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright Andrew Martin (c) 2016
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * 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.
+
+    * Neither the name of Andrew Martin nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"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 COPYRIGHT
+OWNER 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.hs b/Setup.hs
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--- /dev/null
+++ b/Setup.hs
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+import Distribution.Simple
+main = defaultMain
diff --git a/colonnade.cabal b/colonnade.cabal
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--- /dev/null
+++ b/colonnade.cabal
@@ -0,0 +1,30 @@
+name:                colonnade
+version:             0.1
+synopsis:            Generic types and functions for columnar encoding and decoding
+description:         Please see README.md
+homepage:            https://github.com/andrewthad/colonnade#readme
+license:             BSD3
+license-file:        LICENSE
+author:              Andrew Martin
+maintainer:          andrew.thaddeus@gmail.com
+copyright:           2016 Andrew Martin
+category:            web
+build-type:          Simple
+cabal-version:       >=1.10
+
+library
+  hs-source-dirs:      src
+  exposed-modules:
+    Colonnade.Types
+    Colonnade.Encoding
+    Colonnade.Decoding
+    Colonnade.Internal.Ap
+  build-depends:
+      base >= 4.7 && < 5
+    , contravariant
+    , vector
+  default-language:    Haskell2010
+
+source-repository head
+  type:     git
+  location: https://github.com/andrewthad/colonnade
diff --git a/src/Colonnade/Decoding.hs b/src/Colonnade/Decoding.hs
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--- /dev/null
+++ b/src/Colonnade/Decoding.hs
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+{-# LANGUAGE RankNTypes          #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+module Colonnade.Decoding where
+
+import Colonnade.Types
+import Data.Functor.Contravariant
+
+-- | Converts the content type of a 'Decoding'. The @'Contravariant' f@
+-- constraint means that @f@ can be 'Headless' but not 'Headed'.
+contramapContent :: forall c1 c2 f a. Contravariant f => (c2 -> c1) -> Decoding f c1 a -> Decoding f c2 a
+contramapContent f = go
+  where
+  go :: forall b. Decoding f c1 b -> Decoding f c2 b
+  go (DecodingPure x) = DecodingPure x
+  go (DecodingAp h decode apNext) =
+    DecodingAp (contramap f h) (decode . f) (go apNext)
+
+headless :: (content -> Either String a) -> Decoding Headless content a
+headless f = DecodingAp Headless f (DecodingPure id)
+
+headed :: content -> (content -> Either String a) -> Decoding Headed content a
+headed h f = DecodingAp (Headed h) f (DecodingPure id)
+
+
diff --git a/src/Colonnade/Encoding.hs b/src/Colonnade/Encoding.hs
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--- /dev/null
+++ b/src/Colonnade/Encoding.hs
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+module Colonnade.Encoding where
+
+import Colonnade.Types
+import qualified Data.Vector as Vector
+
+mapContent :: Functor f => (c1 -> c2) -> Encoding f c1 a -> Encoding f c2 a
+mapContent f (Encoding v) = Encoding
+  $ Vector.map (\(h,c) -> (fmap f h,f . c)) v
+
+headless :: (a -> content) -> Encoding Headless content a
+headless f = Encoding (Vector.singleton (Headless,f))
+
+headed :: content -> (a -> content) -> Encoding Headed content a
+headed h f = Encoding (Vector.singleton (Headed h,f))
+
diff --git a/src/Colonnade/Internal/Ap.hs b/src/Colonnade/Internal/Ap.hs
new file mode 100644
--- /dev/null
+++ b/src/Colonnade/Internal/Ap.hs
@@ -0,0 +1,47 @@
+{-# LANGUAGE Rank2Types #-}
+{-# LANGUAGE GADTs #-}
+{-# OPTIONS_GHC -Wall #-}
+
+module Colonnade.Internal.Ap
+  ( Ap(..)
+  , runAp
+  , runAp_
+  , liftAp
+  , hoistAp
+  , retractAp
+  ) where
+
+import Control.Applicative
+
+-- | The free 'Applicative' for a 'Functor' @f@.
+data Ap f a where
+  Pure :: a -> Ap f a
+  Ap   :: f a -> Ap f (a -> b) -> Ap f b
+
+runAp :: Applicative g => (forall x. f x -> g x) -> Ap f a -> g a
+runAp _ (Pure x) = pure x
+runAp u (Ap f x) = flip id <$> u f <*> runAp u x
+
+runAp_ :: Monoid m => (forall a. f a -> m) -> Ap f b -> m
+runAp_ f = getConst . runAp (Const . f)
+
+instance Functor (Ap f) where
+  fmap f (Pure a)   = Pure (f a)
+  fmap f (Ap x y)   = Ap x ((f .) <$> y)
+
+instance Applicative (Ap f) where
+  pure = Pure
+  Pure f <*> y = fmap f y
+  Ap x y <*> z = Ap x (flip <$> y <*> z)
+
+liftAp :: f a -> Ap f a
+liftAp x = Ap x (Pure id)
+{-# INLINE liftAp #-}
+
+hoistAp :: (forall a. f a -> g a) -> Ap f b -> Ap g b
+hoistAp _ (Pure a) = Pure a
+hoistAp f (Ap x y) = Ap (f x) (hoistAp f y)
+
+retractAp :: Applicative f => Ap f a -> f a
+retractAp (Pure a) = pure a
+retractAp (Ap x y) = x <**> retractAp y
diff --git a/src/Colonnade/Types.hs b/src/Colonnade/Types.hs
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--- /dev/null
+++ b/src/Colonnade/Types.hs
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+{-# LANGUAGE DeriveFunctor #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE GADTs #-}
+module Colonnade.Types
+  ( Encoding(..)
+  , Decoding(..)
+  , Headed(..)
+  , Headless(..)
+  ) where
+
+import Data.Vector (Vector)
+import Data.Functor.Contravariant (Contravariant(..))
+import Data.Functor.Contravariant.Divisible (Divisible(..))
+import qualified Data.Vector as Vector
+
+-- | Isomorphic to 'Identity'
+newtype Headed a = Headed { getHeaded :: a }
+  deriving (Eq,Ord,Functor,Show,Read)
+
+-- | Isomorphic to 'Proxy'
+data Headless a = Headless
+  deriving (Eq,Ord,Functor,Show,Read)
+
+instance Contravariant Headless where
+  contramap _ Headless = Headless
+
+-- | This just actually a specialization of the free applicative.
+--   Check out @Control.Applicative.Free@ in the @free@ library to
+--   learn more about this.
+data Decoding f content a where
+  DecodingPure :: !a
+               -> Decoding f content a
+  DecodingAp :: !(f content)
+             -> !(content -> Either String a)
+             -> !(Decoding f content (a -> b))
+             -> Decoding f content b
+
+instance Functor (Decoding f content) where
+  fmap f (DecodingPure a) = DecodingPure (f a)
+  fmap f (DecodingAp h c apNext) = DecodingAp h c ((f .) <$> apNext)
+
+instance Applicative (Decoding f content) where
+  pure = DecodingPure
+  DecodingPure f <*> y = fmap f y
+  DecodingAp h c y <*> z = DecodingAp h c (flip <$> y <*> z)
+
+newtype Encoding f content a = Encoding
+  { getEncoding :: Vector (f content,a -> content) }
+  deriving (Monoid)
+
+instance Contravariant (Encoding f content) where
+  contramap f (Encoding v) = Encoding
+    (Vector.map (\(h,c) -> (h, c . f)) v)
+
+instance Divisible (Encoding f content) where
+  conquer = Encoding Vector.empty
+  divide f (Encoding a) (Encoding b) =
+    Encoding $ (Vector.++)
+      (Vector.map (\(h,c) -> (h,c . fst . f)) a)
+      (Vector.map (\(h,c) -> (h,c . snd . f)) b)
+
+