diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright John Ky (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 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/README.md b/README.md
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--- /dev/null
+++ b/README.md
@@ -0,0 +1,6 @@
+# hw-packed-vector
+[![CircleCI](https://circleci.com/gh/haskell-works/hw-packed-vector/tree/0-branch.svg?style=svg)](https://circleci.com/gh/haskell-works/hw-packed-vector/tree/0-branch)
+
+A vector that stores words of equal size between 1 to 64 inclusive in memory contiguously
+with efficient lookup.
+
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/hw-packed-vector.cabal b/hw-packed-vector.cabal
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--- /dev/null
+++ b/hw-packed-vector.cabal
@@ -0,0 +1,53 @@
+name:                   hw-packed-vector
+version:                0.0.0.1
+synopsis:               Packed Vector
+description:            Please see README.md
+homepage:               http://github.com/haskell-works/hw-packed-vector#readme
+license:                BSD3
+license-file:           LICENSE
+author:                 John Ky
+maintainer:             newhoggy@gmail.com
+copyright:              2016 John Ky
+category:               Data, Vector
+stability:              Experimental
+build-type:             Simple
+extra-source-files:     README.md
+cabal-version:          >= 1.22
+
+library
+  hs-source-dirs:       src
+  exposed-modules:      HaskellWorks.Data.PackedVector
+                      , HaskellWorks.Data.PackedVector.Internal
+                      , HaskellWorks.Data.PackedVector.PackedVector64
+  build-depends:        base                          >= 4          && < 5
+                      , bytestring
+                      , hw-bits                       >= 0.4.0.0
+                      , hw-int                        >= 0.0.0.1
+                      , hw-prim                       >= 0.4.0.0
+                      , hw-string-parse               >= 0.0.0.1
+                      , safe
+                      , vector
+
+  default-language:     Haskell2010
+  ghc-options:          -Wall -O2 -msse4.2
+
+test-suite hw-packed-vector-test
+  type:                 exitcode-stdio-1.0
+  hs-source-dirs:       test
+  main-is:              Spec.hs
+  other-modules:        HaskellWorks.Data.PackedVector.PackedVector64Spec
+                      , HaskellWorks.Data.PackedVector.InternalSpec
+  build-depends:        base                          >= 4          && < 5
+                      , bytestring
+                      , hspec
+                      , hw-bits                       >= 0.4.0.0
+                      , hw-packed-vector
+                      , hw-prim                       >= 0.4.0.0
+                      , QuickCheck
+                      , vector
+  ghc-options:          -threaded -rtsopts -with-rtsopts=-N -Wall
+  default-language:     Haskell2010
+
+source-repository head
+  type:     git
+  location: https://github.com/haskell-works/hw-packed-vector
diff --git a/src/HaskellWorks/Data/PackedVector.hs b/src/HaskellWorks/Data/PackedVector.hs
new file mode 100644
--- /dev/null
+++ b/src/HaskellWorks/Data/PackedVector.hs
@@ -0,0 +1,8 @@
+{-# LANGUAGE MultiParamTypeClasses #-}
+
+module HaskellWorks.Data.PackedVector
+    ( module X
+    ) where
+
+import           HaskellWorks.Data.PackedVector.Internal       as X
+import           HaskellWorks.Data.PackedVector.PackedVector64 as X
diff --git a/src/HaskellWorks/Data/PackedVector/Internal.hs b/src/HaskellWorks/Data/PackedVector/Internal.hs
new file mode 100644
--- /dev/null
+++ b/src/HaskellWorks/Data/PackedVector/Internal.hs
@@ -0,0 +1,72 @@
+module HaskellWorks.Data.PackedVector.Internal
+  ( packBits
+  , packBits'
+  , unpackBits
+  , unpackBits'
+  ) where
+
+import           Data.Word
+import           HaskellWorks.Data.Bits.BitWise
+import           HaskellWorks.Data.Bits.FixedBitSize
+import           HaskellWorks.Data.Bits.LoBitsSized
+import           HaskellWorks.Data.Positioning
+
+{-# ANN module ("HLint: Reduce duplication" :: String) #-}
+
+class Integral a => PackBits a where
+  packBits :: Count -> [a] -> [a]
+  packBits = packBits' 0 0
+
+  packBits' :: Count -> a -> Count -> [a] -> [a]
+
+class Integral a => UnpackBits a where
+  unpackBits :: Int -> Count -> [a] -> [a]
+  unpackBits = unpackBits' 0 0
+
+  unpackBits' :: Count -> a -> Int -> Count -> [a] -> [a]
+
+instance PackBits Word64 where
+  packBits' filled carry bitLen (w:ws) = if fillNeeded < fromIntegral (fixedBitSize carry)
+      then packBits' fillNeeded newV bitLen ws
+      else newV : packBits' fillLeft carryV bitLen ws
+    where fillNeeded  = filled + bitLen
+          fillMet     = fillNeeded `min` fromIntegral (fixedBitSize carry)
+          fillLeft    = fillNeeded - fillMet
+          bitMet      = fromIntegral (fillMet - filled) :: Count
+          newV        = carry .|. ((w .&. loBitsSized bitMet) .<. fromIntegral filled)
+          carryV      = w .>. bitMet
+  packBits' _ carry _ _ = [carry]
+
+instance UnpackBits Word64 where
+  unpackBits' _ _ 0 _ _ = []
+  unpackBits' filled carry dataLen bitLen ws | filled >= bitLen =
+    let result = (carry .&. loBitsSized bitLen) : unpackBits' (filled - bitLen) (carry .>. fromIntegral bitLen) (dataLen - 1) bitLen ws in
+    result
+  unpackBits' filled carry dataLen bitLen (w:ws) =
+    let bitsNeeded = bitLen - filled                    in
+    let newValue = carry .|. ((w .&. loBitsSized bitsNeeded) .<. fromIntegral filled) in
+    newValue : unpackBits' (fromIntegral (fixedBitSize carry) - bitsNeeded) (w .>. fromIntegral bitsNeeded) (dataLen - 1) bitLen ws
+  unpackBits' _ _ _ _ _ = []
+
+instance PackBits Word8 where
+  packBits' filled carry bitLen (w:ws) = if fillNeeded < fromIntegral (fixedBitSize carry)
+      then packBits' fillNeeded newV bitLen ws
+      else newV : packBits' fillLeft carryV bitLen ws
+    where fillNeeded  = filled + bitLen
+          fillMet     = fillNeeded `min` fromIntegral (fixedBitSize carry)
+          fillLeft    = fillNeeded - fillMet
+          bitMet      = fromIntegral (fillMet - filled) :: Count
+          newV        = carry .|. ((w .&. loBitsSized bitMet) .<. fromIntegral filled)
+          carryV      = w .>. fromIntegral bitMet
+  packBits' _ carry _ _ = [carry]
+
+instance UnpackBits Word8 where
+  unpackBits' _ _ 0 _ _ = []
+  unpackBits' filled carry dataLen bitLen ws | filled >= bitLen =
+    (carry .&. loBitsSized bitLen) : unpackBits' (filled - bitLen) (carry .>. fromIntegral bitLen) (dataLen - 1) bitLen ws
+  unpackBits' filled carry dataLen bitLen (w:ws) =
+    let bitsNeeded = bitLen - filled                    in
+    let newValue = carry .|. ((w .&. loBitsSized bitsNeeded) .<. fromIntegral filled) in
+    let result = newValue : unpackBits' (8 - bitsNeeded) (w .>. fromIntegral bitsNeeded) (dataLen - 1) bitLen ws in
+    result
+  unpackBits' _ _ _ _ _ = []
diff --git a/src/HaskellWorks/Data/PackedVector/PackedVector64.hs b/src/HaskellWorks/Data/PackedVector/PackedVector64.hs
new file mode 100644
--- /dev/null
+++ b/src/HaskellWorks/Data/PackedVector/PackedVector64.hs
@@ -0,0 +1,70 @@
+{-# LANGUAGE TypeFamilies #-}
+
+module HaskellWorks.Data.PackedVector.PackedVector64
+  ( PackedVector64(..)
+  , empty
+  , fromList
+  , toList
+  ) where
+
+import qualified Data.Vector.Storable as DVS
+import           Data.Int
+import           Data.Word
+import           HaskellWorks.Data.AtIndex
+import           HaskellWorks.Data.Bits.BitWise
+import           HaskellWorks.Data.Bits.LoBitsSized
+import           HaskellWorks.Data.PackedVector.Internal
+import           HaskellWorks.Data.Positioning
+import           HaskellWorks.Data.Unsign
+import           Prelude hiding (length)
+
+data PackedVector64 = PackedVector64
+    { swBuffer      :: !(DVS.Vector Word64)
+    , swBitSize     :: !Word
+    , swBufferLen   :: !Int
+    } deriving (Eq, Show)
+
+empty :: PackedVector64
+empty =
+  PackedVector64
+  { swBuffer    = DVS.empty
+  , swBufferLen = 0
+  , swBitSize   = 1
+  }
+
+instance Container PackedVector64 where
+  type Elem PackedVector64 = Word64
+
+instance Length PackedVector64 where
+  length = fromIntegral . swBufferLen
+  {-# INLINE length #-}
+
+instance AtIndex PackedVector64 where
+  atIndex v i =
+    let bitSize     = fromIntegral (swBitSize v) :: Count
+        bitIndex    = fromIntegral (swBitSize v) * i
+        (q, r)      = bitIndex `quotRem` 64
+        vv          = swBuffer v
+    in if r <= 64 - fromIntegral bitSize
+      then -- Not crossing boundary
+        ((vv !!! q) .>. unsign r) .&. loBitsSized bitSize
+      else -- Crossing boundary
+        let loBitsSize  = 64 - toCount r
+            hiBitsSize  = bitSize - loBitsSize
+            loBits      = ((vv !!! q) .>. unsign r) .&. loBitsSized loBitsSize
+            hiBits      = if r > 64 - fromIntegral bitSize then (vv !!! (q + 1)) .&. loBitsSized hiBitsSize else 0
+        in  loBits .|. (hiBits .<. loBitsSize)
+  (!!!)       = atIndex
+  {-# INLINE (!!!)   #-}
+  {-# INLINE atIndex #-}
+
+fromList :: Count -> [Word64] -> PackedVector64
+fromList wl ws =
+  PackedVector64
+  { swBuffer    = DVS.fromList (packBits wl ws)
+  , swBufferLen = fromIntegral (length ws)
+  , swBitSize   = fromIntegral wl
+  }
+
+toList :: PackedVector64 -> [Word64]
+toList v = unpackBits (swBufferLen v) (fromIntegral (swBitSize v)) (DVS.toList (swBuffer v))
diff --git a/test/HaskellWorks/Data/PackedVector/InternalSpec.hs b/test/HaskellWorks/Data/PackedVector/InternalSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/HaskellWorks/Data/PackedVector/InternalSpec.hs
@@ -0,0 +1,38 @@
+{-# OPTIONS_GHC -fno-warn-incomplete-patterns #-}
+{-# LANGUAGE    ScopedTypeVariables           #-}
+
+module HaskellWorks.Data.PackedVector.InternalSpec (spec) where
+
+import           Data.Word
+import           HaskellWorks.Data.Bits.BitWise
+import           HaskellWorks.Data.PackedVector.Internal
+import           HaskellWorks.Data.Positioning
+import           Test.Hspec
+import           Test.QuickCheck
+
+{-# ANN module ("HLint: Ignore Redundant do" :: String) #-}
+
+subWordSize :: Count -> Gen Count
+subWordSize maxWordSize = choose (1, maxWordSize)
+
+word8OfSize :: Count -> Gen Word8
+word8OfSize sz = choose (0, 1 .<. fromIntegral sz - 1)
+
+word64OfSize :: Count -> Gen Word64
+word64OfSize sz = choose (0, 1 .<. fromIntegral sz - 1)
+
+listLen :: Gen Int
+listLen = choose (1, 128)
+
+spec :: Spec
+spec = describe "HaskellWorks.Data.PackedVector.InternalSpec" $ do
+  it "PackedVector Word8" $
+    forAll (subWordSize 8) $ \wSize ->
+      forAll (choose (1, 3)) $ \len ->
+        forAll (vectorOf len (word8OfSize wSize)) $ \ws ->
+          unpackBits (length ws) wSize (packBits wSize ws) `shouldBe` ws
+  it "PackedVector Word64" $
+    forAll (subWordSize 64) $ \wSize ->
+      forAll listLen $ \len ->
+        forAll (vectorOf len (word64OfSize wSize)) $ \ws ->
+          unpackBits (length ws) wSize (packBits wSize ws) `shouldBe` ws
diff --git a/test/HaskellWorks/Data/PackedVector/PackedVector64Spec.hs b/test/HaskellWorks/Data/PackedVector/PackedVector64Spec.hs
new file mode 100644
--- /dev/null
+++ b/test/HaskellWorks/Data/PackedVector/PackedVector64Spec.hs
@@ -0,0 +1,37 @@
+{-# OPTIONS_GHC -fno-warn-incomplete-patterns #-}
+{-# LANGUAGE    ScopedTypeVariables           #-}
+
+module HaskellWorks.Data.PackedVector.PackedVector64Spec (spec) where
+
+import           Data.Word
+import           HaskellWorks.Data.AtIndex
+import           HaskellWorks.Data.Bits.BitWise
+import           HaskellWorks.Data.PackedVector.PackedVector64
+import           HaskellWorks.Data.Positioning
+import           Test.Hspec
+import           Test.QuickCheck
+
+{-# ANN module ("HLint: Ignore Redundant do" :: String) #-}
+
+subWordSize :: Count -> Gen Count
+subWordSize maxWordSize = choose (1, maxWordSize)
+
+word64OfSize :: Count -> Gen Word64
+word64OfSize sz = choose (0, 1 .<. fromIntegral sz - 1)
+
+listLen :: Gen Int
+listLen = choose (1, 128)
+
+spec :: Spec
+spec = describe "HaskellWorks.Data.PackedVector.PackedVector64Spec" $ do
+  it "Round trip from list" $
+    forAll (subWordSize 64) $ \wSize ->
+      forAll listLen $ \len ->
+        forAll (vectorOf len (word64OfSize wSize)) $ \ws ->
+          toList (fromList wSize ws) `shouldBe` ws
+  it "Round trip from list" $
+    forAll (subWordSize 64) $ \wSize ->
+      forAll (choose (1, 32 :: Int)) $ \len ->
+        forAll (vectorOf len (word64OfSize wSize)) $ \ws ->
+          forAll (choose (0, fromIntegral len - 1 :: Position)) $ \i ->
+            (fromList wSize ws !!! i) `shouldBe` (ws !!! i)
diff --git a/test/Spec.hs b/test/Spec.hs
new file mode 100644
--- /dev/null
+++ b/test/Spec.hs
@@ -0,0 +1,1 @@
+{-# OPTIONS_GHC -F -pgmF hspec-discover #-}