diff --git a/CHANGELOG.md b/CHANGELOG.md
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--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,7 @@
+# Change log
+
+DataIndex uses [Semantic Versioning][].
+The change log is available through the [releases on GitHub][].
+
+[Semantic Versioning]: http://semver.org/spec/v2.0.0.html
+[releases on GitHub]: https://github.com/yuhangwang/DataIndex/releases
diff --git a/DataIndex.cabal b/DataIndex.cabal
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--- /dev/null
+++ b/DataIndex.cabal
@@ -0,0 +1,74 @@
+-- This file has been generated from package.yaml by hpack version 0.14.0.
+--
+-- see: https://github.com/sol/hpack
+
+name:           DataIndex
+version:        0.1.0
+synopsis:       A package for adding index column to data files
+description:    DataIndex can add index column to data files
+category:       Data
+homepage:       https://github.com/yuhangwang/DataIndex#readme
+bug-reports:    https://github.com/yuhangwang/DataIndex/issues
+maintainer:     Yuhang(Steven) Wang
+license:        MIT
+license-file:   LICENSE.md
+build-type:     Simple
+cabal-version:  >= 1.10
+
+extra-source-files:
+    CHANGELOG.md
+    LICENSE.md
+    package.yaml
+    README.md
+    stack.yaml
+
+source-repository head
+  type: git
+  location: https://github.com/yuhangwang/DataIndex
+
+library
+  hs-source-dirs:
+      library
+  ghc-options: -Wall
+  build-depends:
+      base
+  exposed-modules:
+      Data.Index
+  default-language: Haskell2010
+
+executable DataIndex
+  main-is: Main.hs
+  hs-source-dirs:
+      executable
+  ghc-options: -Wall -rtsopts -threaded -with-rtsopts=-N
+  build-depends:
+      base >= 4 && < 5
+    , DataIndex
+  default-language: Haskell2010
+
+test-suite DataIndex-test-suite
+  type: exitcode-stdio-1.0
+  main-is: Main.hs
+  hs-source-dirs:
+      test-suite
+  ghc-options: -Wall -rtsopts -threaded -with-rtsopts=-N
+  build-depends:
+      base
+    , DataIndex
+    , tasty
+    , tasty-hspec
+  other-modules:
+      Spec_addTime
+  default-language: Haskell2010
+
+benchmark DataIndex-benchmarks
+  type: exitcode-stdio-1.0
+  main-is: Main.hs
+  hs-source-dirs:
+      benchmark
+  ghc-options: -Wall -rtsopts -threaded -with-rtsopts=-N
+  build-depends:
+      base
+    , DataIndex
+    , criterion
+  default-language: Haskell2010
diff --git a/LICENSE.md b/LICENSE.md
new file mode 100644
--- /dev/null
+++ b/LICENSE.md
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2016 Steven(Yuhang) Wang
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
new file mode 100644
--- /dev/null
+++ b/README.md
@@ -0,0 +1,2 @@
+# DataIndex
+A Haskell package for adding index columns to data files
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,7 @@
+-- This script is used to build and install your package. Typically you don't
+-- need to change it. The Cabal documentation has more information about this
+-- file: <https://www.haskell.org/cabal/users-guide/installing-packages.html>.
+import qualified Distribution.Simple
+
+main :: IO ()
+main = Distribution.Simple.defaultMain
diff --git a/benchmark/Main.hs b/benchmark/Main.hs
new file mode 100644
--- /dev/null
+++ b/benchmark/Main.hs
@@ -0,0 +1,6 @@
+-- You can benchmark your code quickly and effectively with Criterion. See its
+-- website for help: <http://www.serpentine.com/criterion/>.
+import Criterion.Main
+
+main :: IO ()
+main = defaultMain [bench "const" (whnf const ())]
diff --git a/executable/Main.hs b/executable/Main.hs
new file mode 100644
--- /dev/null
+++ b/executable/Main.hs
@@ -0,0 +1,45 @@
+import Data.Index
+import System.Environment
+import System.Exit
+import Data.List
+
+main :: IO ()
+main = do
+    args <- getArgs
+    exe args
+
+usage :: String
+usage = "USAGE: DataIndex output.data input.dat"
+
+exe :: [String] -> IO ()
+exe [] = do 
+    putStrLn usage
+    exitFailure
+
+exe [_] = do 
+    putStrLn usage
+    exitFailure
+exe [_,_] = do 
+    putStrLn usage
+    exitFailure
+
+exe (output:input:time_unit:_) = do
+    content <- readFile input
+    let dat = loadData content
+    let unit = read time_unit :: Float
+    save output (addTime dat unit)
+
+loadData :: String -> [[Float]]
+loadData content = fmap ((fmap read) . words) (lines content)
+
+array2str :: Show a => [[a]] -> String 
+array2str [] = ""
+array2str array = aux array []
+    where
+        aux :: Show a => [[a]] -> [String] -> String
+        aux [] accum = intercalate "\n" (reverse accum)
+        aux (x:xs) accum = aux xs ((unwords (map show x)):accum)
+
+save :: Show a => String -> [[a]] -> IO ()
+save output_file dat = do
+    writeFile output_file (array2str dat)
diff --git a/library/Data/Index.hs b/library/Data/Index.hs
new file mode 100644
--- /dev/null
+++ b/library/Data/Index.hs
@@ -0,0 +1,18 @@
+-- | Data.Index is a package for adding index column to data files
+module Data.Index 
+    ( hello
+    , addTime) where
+
+-- | say hello
+hello :: String
+hello = "Hello Data.Index!"
+
+-- | Add an time column
+-- usage: addTime <data array> <time unit>
+addTime :: Num a => [[a]] -> a -> [[a]]
+addTime array time_unit = aux array time_unit []
+    where
+        aux :: Num a => [[a]] -> a -> [[a]] -> [[a]]
+        aux [] _ accum = reverse accum
+        aux (x:xs) unit accum = aux xs unit ((i:x):accum)
+            where i = unit * (fromIntegral ((length accum) + 1))
diff --git a/package.yaml b/package.yaml
new file mode 100644
--- /dev/null
+++ b/package.yaml
@@ -0,0 +1,56 @@
+benchmarks:
+  DataIndex-benchmarks:
+    dependencies:
+    - base
+    - DataIndex
+    - criterion
+    ghc-options:
+    - -rtsopts
+    - -threaded
+    - -with-rtsopts=-N
+    main: Main.hs
+    source-dirs: benchmark
+category: Data
+description: DataIndex can add index column to data files
+executables:
+  DataIndex:
+    dependencies:
+    - base >= 4 && < 5
+    - DataIndex
+    ghc-options:
+    - -rtsopts
+    - -threaded
+    - -with-rtsopts=-N
+    main: Main.hs
+    source-dirs: executable
+extra-source-files:
+- CHANGELOG.md
+- LICENSE.md
+- package.yaml
+- README.md
+- stack.yaml
+ghc-options: -Wall
+github: yuhangwang/DataIndex
+library:
+  dependencies:
+  - base
+  source-dirs: library
+license: MIT
+license-file: LICENSE.md
+maintainer: Yuhang(Steven) Wang
+name: DataIndex
+synopsis: A package for adding index column to data files
+tests:
+  DataIndex-test-suite:
+    dependencies:
+    - base
+    - DataIndex
+    - tasty
+    - tasty-hspec
+    ghc-options:
+    - -rtsopts
+    - -threaded
+    - -with-rtsopts=-N
+    main: Main.hs
+    source-dirs: test-suite
+version: '0.1.0'
diff --git a/stack.yaml b/stack.yaml
new file mode 100644
--- /dev/null
+++ b/stack.yaml
@@ -0,0 +1,66 @@
+# This file was automatically generated by 'stack init'
+# 
+# Some commonly used options have been documented as comments in this file.
+# For advanced use and comprehensive documentation of the format, please see:
+# http://docs.haskellstack.org/en/stable/yaml_configuration/
+
+# Resolver to choose a 'specific' stackage snapshot or a compiler version.
+# A snapshot resolver dictates the compiler version and the set of packages
+# to be used for project dependencies. For example:
+# 
+# resolver: lts-3.5
+# resolver: nightly-2015-09-21
+# resolver: ghc-7.10.2
+# resolver: ghcjs-0.1.0_ghc-7.10.2
+# resolver:
+#  name: custom-snapshot
+#  location: "./custom-snapshot.yaml"
+resolver: lts-7.2
+
+# User packages to be built.
+# Various formats can be used as shown in the example below.
+# 
+# packages:
+# - some-directory
+# - https://example.com/foo/bar/baz-0.0.2.tar.gz
+# - location:
+#    git: https://github.com/commercialhaskell/stack.git
+#    commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+# - location: https://github.com/commercialhaskell/stack/commit/e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+#   extra-dep: true
+#  subdirs:
+#  - auto-update
+#  - wai
+# 
+# A package marked 'extra-dep: true' will only be built if demanded by a
+# non-dependency (i.e. a user package), and its test suites and benchmarks
+# will not be run. This is useful for tweaking upstream packages.
+packages:
+- '.'
+# Dependency packages to be pulled from upstream that are not in the resolver
+# (e.g., acme-missiles-0.3)
+extra-deps: []
+
+# Override default flag values for local packages and extra-deps
+flags: {}
+
+# Extra package databases containing global packages
+extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+# 
+# Require a specific version of stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: ">=1.1"
+# 
+# Override the architecture used by stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+# 
+# Extra directories used by stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+# 
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor
diff --git a/test-suite/Main.hs b/test-suite/Main.hs
new file mode 100644
--- /dev/null
+++ b/test-suite/Main.hs
@@ -0,0 +1,9 @@
+import qualified Test.Tasty
+import Test.Tasty.Hspec
+import Spec_addTime
+
+main :: IO ()
+main = do
+    test <- testSpec "addTime" test_addTime
+    Test.Tasty.defaultMain test
+
diff --git a/test-suite/Spec_addTime.hs b/test-suite/Spec_addTime.hs
new file mode 100644
--- /dev/null
+++ b/test-suite/Spec_addTime.hs
@@ -0,0 +1,20 @@
+module Spec_addTime (test_addTime) where 
+import Data.Index
+import Test.Tasty.Hspec
+
+test_addTime :: Spec
+test_addTime = parallel $ do
+    it "addTime [] 1. should return []" $ do
+        (addTime [] (1.0::Double)) `shouldBe` []
+
+    it "addTime [[1],[2]] 1 should return [[1,1],[2,2]]" $ do
+        (addTime [[1],[2]] (1::Int)) `shouldBe` [[1,1],[2,2]]
+
+    it "addTime [[1,10],[2,20]] 1 should return [[1,1,10],[2,2,20]]" $ do
+        (addTime [[1,10],[2,20]] (1::Int)) `shouldBe` [[1,1,10],[2,2,20]]
+
+    it "addTime [[1],[2]] 2 should return [[2,1],[4,2]]" $ do
+        (addTime [[1],[2]] (2::Int)) `shouldBe` [[2,1],[4,2]]
+
+    it "addTime [[1.0],[2.0]] 1 should return [[1.0,1.0],[2.0,2.0]]" $ do
+        (addTime [[1.0],[2.0]] (1.0::Float)) `shouldBe` [[1.0,1.0],[2.0,2.0]]
