diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright Author name here (c) 2015
+
+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 Author name here 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
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/data-extend-generic.cabal b/data-extend-generic.cabal
new file mode 100644
--- /dev/null
+++ b/data-extend-generic.cabal
@@ -0,0 +1,35 @@
+name:                data-extend-generic
+version:             0.1.0.0
+synopsis:            Extend Haskell data or newtype like in OOP languages
+description:         This package allows you to extend Haskell data or newtype like in OOP languages.
+homepage:            http://github.com/githubuser/data-extend-generic#readme
+license:             BSD3
+license-file:        LICENSE
+author:              Yu Li
+maintainer:          ylilarry@gmail.com
+copyright:           2010 Yu Li
+category:            Data
+build-type:          Simple
+-- extra-source-files:
+cabal-version:       >=1.10
+
+library
+  hs-source-dirs:      src
+  exposed-modules:     Data.Extend
+                     , Data.Extend.Internal
+  build-depends:       base >= 4.7 && < 5
+  default-language:    Haskell2010
+
+test-suite data-extend-generic-test
+  type:                exitcode-stdio-1.0
+  hs-source-dirs:      test
+  main-is:             Spec.hs
+  build-depends:       base
+                     , data-extend-generic
+                     , hspec
+  ghc-options:         -threaded -rtsopts -with-rtsopts=-N
+  default-language:    Haskell2010
+
+source-repository head
+  type:     git
+  location: https://github.com/githubuser/data-extend-generic
diff --git a/src/Data/Extend.hs b/src/Data/Extend.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Extend.hs
@@ -0,0 +1,44 @@
+{-# LANGUAGE Safe #-}
+----------------------------------------------------------------------------------
+-- |
+-- Module      : Data.Extend
+-- Copyright   : (c) Yu Li, 2015
+-- License     : BSD
+-- Maintainer  : ylilarry@gmail.com
+-- Stability   : experimental
+-- Portability : GHC extensions
+--
+-- This package allows you to extend a Haskell data like how you do in OOP.
+--
+-- Here is an example use for testing:
+--
+-- >
+-- > data Test = Test | TestA {
+-- >       f1 :: Int,
+-- >       f2 :: Maybe Int,
+-- >       f3 :: Maybe Int
+-- >    } deriving (Show, Generic, Eq)
+-- >
+-- > test1A = TestA 1 (Just 1) (Just 3)
+-- > test2A = TestA 0 Nothing (Just 2)
+-- >
+-- > main :: IO ()
+-- > main = hspec $
+-- >    describe "Data.Extend" $ do
+-- >       specify "Int" $
+-- >          (2 `extend` 1) `shouldBe` (2 :: Int)
+-- >       specify "String" $
+-- >          ("b" `extend` "a") `shouldBe` "b"
+-- >       specify "data 0" $
+-- >          (Test `extend` Test) `shouldBe` Test
+-- >       specify "data 1" $
+-- >          (test2A `extend` test1A) `shouldBe` TestA 0 (Just 1) (Just 2)
+-- >
+--
+----------------------------------------------------------------------------------
+
+module Data.Extend (
+      Extend(..)
+   ) where
+
+import Data.Extend.Internal
diff --git a/src/Data/Extend/Internal.hs b/src/Data/Extend/Internal.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Extend/Internal.hs
@@ -0,0 +1,65 @@
+{-# LANGUAGE Safe #-}
+{-# LANGUAGE TypeOperators #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# LANGUAGE DefaultSignatures #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE FlexibleContexts #-}
+
+module Data.Extend.Internal where
+
+import Control.Applicative
+import GHC.Generics
+
+
+class GExtend a where
+   gExtend :: a p -> a p -> a p
+
+
+instance (GExtend (K1 i (m a)), Alternative m, GExtend b) => GExtend (K1 i (m a) :*: b) where
+   gExtend (K1 a1 :*: b1) (K1 a2 :*: b2) = K1 (a1 <|> a2) :*: gExtend b1 b2
+
+instance GExtend U1 where
+   gExtend _ _ = U1
+
+instance (Extend a) => GExtend (K1 i a) where
+   gExtend (K1 a) (K1 b) = K1 $ extend a b
+
+instance (GExtend a, GExtend b) => GExtend (a :*: b) where
+   gExtend (a1 :*: b1) (a2 :*: b2) = gExtend a1 a2 :*: gExtend b1 b2
+
+instance (GExtend a, GExtend b) => GExtend (a :+: b) where
+   gExtend (L1 a) (L1 b) = L1 $ gExtend a b
+   gExtend (R1 a) (R1 b) = R1 $ gExtend a b
+   gExtend a _ = a
+
+instance (GExtend a) => GExtend (M1 i c a) where
+   gExtend (M1 a) (M1 b) = M1 $ gExtend a b
+
+
+class Extend a where
+   -- | By default
+   --
+   -- prop>  a `extend` b = a
+   --
+   -- prop> Nothing `extend` Just a = Just a
+   --
+   -- To use the "Extend" class, simply make your data derive Generic.
+   --
+   -- If "a" is a user defined data type, then all "Nothing" fields of "a" are replaced by corresponding fields in "b",
+   --
+   -- ie, all "Just" fields in "a" will override corresponding fields in "b".
+   extend :: a -> a -> a
+   default extend :: (Generic a, GExtend (Rep a)) => a -> a -> a
+   extend a b = to $ gExtend (from a) (from b)
+
+
+instance (Extend a) => Extend (Maybe a) where
+   -- | Nothing `extend` Just b = Just b
+   -- (Just a) `extend` (Just b) = Just a
+   extend (Just a) _ = Just a
+   extend Nothing  b = b
+
+instance {-# OVERLAPPABLE #-} Extend a where
+   -- | By default a `extend` b is a
+   extend a _ = a
+
diff --git a/test/Spec.hs b/test/Spec.hs
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--- /dev/null
+++ b/test/Spec.hs
@@ -0,0 +1,50 @@
+{-# LANGUAGE DeriveGeneric #-}
+
+import Test.Hspec
+import Data.Extend
+import GHC.Generics
+
+
+data Test = Test | TestA {
+      f1 :: Int,
+      f2 :: Maybe Int,
+      f3 :: Maybe Int
+   } | TestB {
+      g1 :: Int,
+      g2 :: Maybe Int,
+      g3 :: Maybe Int
+   } deriving (Show, Generic, Eq)
+
+test1A = TestA 1 (Just 1) Nothing
+test2A = TestA 0 Nothing (Just 2)
+
+test1B = TestB 1 (Just 1) Nothing
+test2B = TestB 0 Nothing (Just 2)
+
+
+
+instance Extend Test
+
+main :: IO ()
+main = hspec $
+   describe "Data.Extend" $ do
+      specify "Int" $
+         (2 `extend` 1) `shouldBe` (2 :: Int)
+      specify "String" $
+         ("b" `extend` "a") `shouldBe` "b"
+      specify "data 0" $
+         (Test `extend` Test) `shouldBe` Test
+      specify "data 1" $
+         (test2A `extend` test1A) `shouldBe` TestA 0 (Just 1) (Just 2)
+      specify "data 2" $
+         (test2B `extend` test1B) `shouldBe` TestB 0 (Just 1) (Just 2)
+      specify "data 3" $
+         (test2B `extend` test1A) `shouldBe` test2B
+      specify "data 4" $
+         (test1A `extend` test2B) `shouldBe` test1A
+      specify "data 5" $
+         (test2A `extend` test1B) `shouldBe` test2A
+      specify "data 6" $
+         (test1B `extend` test2A) `shouldBe` test1B
+
+