diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,20 @@
+Copyright (c) 2015 Nils 'bash0r' Jonsson
+
+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/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/headergen.cabal b/headergen.cabal
new file mode 100644
--- /dev/null
+++ b/headergen.cabal
@@ -0,0 +1,81 @@
+-- Initial headergen.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+-- The name of the package.
+name:                headergen
+
+-- The package version.  See the Haskell package versioning policy (PVP) 
+-- for standards guiding when and how versions should be incremented.
+-- http://www.haskell.org/haskellwiki/Package_versioning_policy
+-- PVP summary:      +-+------- breaking API changes
+--                   | | +----- non-breaking API additions
+--                   | | | +--- code changes with no API change
+version:             0.1.0.0
+
+homepage:            https://github.com/aka-bash0r/headergen
+
+-- A short (one-line) description of the package.
+synopsis:            Creates a header for a haskell source file.
+
+-- A longer description of the package.
+description:         The headergen package provides a small utility for
+                     creating documentation headers for source files.
+
+-- The license under which the package is released.
+license:             MIT
+
+-- The file containing the license text.
+license-file:        LICENSE
+
+-- The package author(s).
+author:              Nils 'bash0r' Jonsson
+
+-- An email address to which users can send suggestions, bug reports, and 
+-- patches.
+maintainer:          aka.bash0r@gmail.com
+
+-- A copyright notice.
+copyright:           (c) 2015 Nils bash0r Jonsson
+
+category:            Development
+
+build-type:          Simple
+
+-- Extra files to be distributed with the package, such as examples or a 
+-- README.
+-- extra-source-files:  
+
+-- Constraint on the version of Cabal needed to build this package.
+cabal-version:       >=1.10
+
+source-repository head
+  type:     git
+  location: https://github.com/aka-bash0r/headergen
+
+
+executable headergen
+  -- .hs or .lhs file containing the Main module.
+  main-is:              Main.hs
+  
+  -- Modules included in this executable, other than Main.
+  -- other-modules:       
+  
+  -- LANGUAGE extensions used by modules in this package.
+  -- other-extensions:    
+  
+  -- Other library packages from which modules are imported.
+  build-depends:        base         >=4.8     && <4.9
+               ,        aeson        >=0.9.0.1 && <0.10
+               ,        aeson-pretty >=0.7.2   && <0.8
+               ,        directory    >=1.2.2   && <1.3
+               ,        filepath     >=1.4     && <1.5
+               ,        time         >=1.5.0.1 && <1.6
+               ,        bytestring   >=0.10.6  && <0.17
+               ,        haskeline    >=0.7.2.1 && <0.8
+
+  -- Directories containing source files.
+  hs-source-dirs:       src
+  
+  -- Base language which the package is written in.
+  default-language:     Haskell2010
+  
diff --git a/src/Main.hs b/src/Main.hs
new file mode 100644
--- /dev/null
+++ b/src/Main.hs
@@ -0,0 +1,249 @@
+{- |
+Module      :  $Header$
+Description :  The main module of the application.
+Copyright   :  (c) 2015 Nils 'bash0r' Jonsson
+License     :  MIT
+
+Maintainer  :  aka.bash0r@gmail.com
+Stability   :  unstable
+Portability :  non-portable (Portability is not tested.)
+
+The main module is the entry point of the application.
+-}
+
+{-# LANGUAGE OverloadedStrings #-}
+
+module Main
+( main
+) where
+
+import Control.Applicative
+import Control.Monad
+
+import Data.Aeson
+import Data.Aeson.Encode.Pretty
+import qualified Data.ByteString.Lazy as BS
+import Data.Time.Clock
+import Data.Time.Calendar
+
+import System.FilePath.Posix
+import System.Console.Haskeline
+import System.Directory
+import System.Environment
+import System.IO
+
+date :: IO (Integer, Int, Int)
+date = liftM (toGregorian . utctDay) getCurrentTime
+
+-- | The configuration is used to read / write configuration to JSON.
+data Configuration = Configuration
+  { getModule      :: String
+  , getDescription :: String
+  , getAuthor      :: String
+  , getCopyright   :: String
+  , getLicense     :: String
+  , getMaintainer  :: String
+  , getStability   :: String
+  , getPortability :: String
+  }
+
+defaultConfiguration = Configuration
+  { getModule      = "$Header$"
+  , getDescription = ""
+  , getAuthor      = ""
+  , getCopyright   = ""
+  , getLicense     = ""
+  , getMaintainer  = ""
+  , getStability   = "unstable"
+  , getPortability = "non-portable (Portability is untested.)"
+  }
+
+instance ToJSON Configuration where
+  toJSON (Configuration mod desc auth copyr lic maint stab portab) =
+    object [ "module"      .= mod
+           , "author"      .= auth
+           , "description" .= desc
+           , "copyright"   .= copyr
+           , "license"     .= lic
+           , "maintainer"  .= maint
+           , "stability"   .= stab
+           , "portability" .= portab
+           ]
+
+instance FromJSON Configuration where
+  parseJSON (Object o) =
+    Configuration <$> o .: "module"
+                  <*> o .: "description"
+                  <*> o .: "author"
+                  <*> o .: "copyright"
+                  <*> o .: "license"
+                  <*> o .: "maintainer"
+                  <*> o .: "stability"
+                  <*> o .: "portability"
+  parseJSON _          =
+    empty
+
+-- | Try to get the parent directory of a given path.
+parentDirectory :: FilePath -> Maybe FilePath
+parentDirectory path =
+  let splitted   = splitDirectories path
+      reversed   = reverse splitted
+      dropped    = drop 1 reversed
+      rereversed = reverse dropped
+      newPath    = joinPath rereversed
+   in case newPath of
+        []        -> Nothing
+        otherwise -> Just otherwise
+
+-- | Traverses the path up to root directory.
+traversePath :: String -> FilePath -> IO ()
+traversePath mod cwd = do
+  putStrLn ("Checking " ++ cwd ++ " ...")
+  let headerGenDef = cwd </> ".headergen.def"
+  exists <- doesFileExist headerGenDef
+  if exists
+     then do
+       h  <- openFile headerGenDef ReadMode
+       cs <- BS.hGetContents h
+       let hgd = decode cs :: Maybe Configuration 
+       case hgd of
+         Just a  -> createHeader mod a
+         Nothing -> printCorruptedMessage
+       hClose h 
+     else case parentDirectory cwd of
+       Just a  -> traversePath mod a
+       Nothing -> printExitMessage
+
+-- | Print message about a corrupted .headergen.def.
+printCorruptedMessage :: IO ()
+printCorruptedMessage = do
+  putStrLn "The .headergen.def is corrupted."
+  putStrLn "Exitting now."
+  putStrLn ""
+
+-- | Print the exit message.
+printExitMessage :: IO ()
+printExitMessage = do
+  putStrLn "There is no .headergen.def in any parent directory."
+  putStrLn "Exitting now."
+  putStrLn ""
+
+requestForAllowance :: IO Bool
+requestForAllowance = runInputT defaultSettings allowanceRequest
+  where
+    allowanceRequest = do
+      line <- getInputLine "File for module exists already. Override? [y/n] "
+      case line of
+        (Just "y") -> return True
+        (Just "n") -> return False
+        _          -> allowanceRequest
+
+-- | Create the header.
+createHeader :: String -> Configuration -> IO ()
+createHeader mod conf = do
+  exists <- doesFileExist mod
+  if exists
+     then do
+       v <- requestForAllowance
+       if v
+          then printHeader mod conf
+          else printExit
+     else printHeader mod conf
+
+printExit :: IO ()
+printExit = do
+  putStrLn "No resources have been created."
+  putStrLn "Exiting now."
+  putStrLn ""
+
+printHeader :: String -> Configuration -> IO ()
+printHeader modFile (Configuration mod des aut cop lic mai sta por) = do
+  h <- openFile modFile WriteMode
+  hPutStrLn h  "{- |"
+  hPutStrLn h ("Module      :  " ++ mod)
+  hPutStrLn h ("Description :  " ++ des)
+  hPutStrLn h ("Author      :  " ++ aut)
+  hPutStrLn h ("Copyright   :  " ++ cop)
+  hPutStrLn h ("License     :  " ++ lic)
+  hPutStrLn h  ""
+  hPutStrLn h ("Maintainer  :  " ++ mai)
+  hPutStrLn h ("Stability   :  " ++ sta)
+  hPutStrLn h ("Portability :  " ++ por)
+  hPutStrLn h  ""
+  hPutStrLn h  "TODO: module description"
+  hPutStrLn h  "-}"
+  hFlush h
+  hClose h
+
+def :: Maybe String -> String -> String
+def v d =
+  case v of
+    Just v ->
+      if null v
+         then d
+         else v
+    Nothing ->
+      d
+
+alignText :: String -> String
+alignText xs =
+  if length xs < 8
+     then alignText (xs ++ " ")
+     else xs
+
+defaultText :: String -> String
+defaultText crt =
+  if length crt >= 8
+     then take 8 crt
+     else alignText crt
+
+requestConfiguration :: IO Configuration
+requestConfiguration = do
+  (year, _, _) <- date
+  runInputT defaultSettings $ do
+    mod    <- getInputLine  "Module      [$Header$]: "
+    desc   <- getInputLine  "Description [        ]: "
+    auth   <- getInputLine  "Author      [        ]: "
+    let copyRightText    = "(c) " ++ show year ++ " " ++ def auth ""
+    copyr  <- getInputLine ("Copyright   [" ++ defaultText copyRightText ++ "]: ")
+    lic    <- getInputLine  "License     [MIT     ]: "
+    maint  <- getInputLine  "Maintainer  [        ]: "
+    stab   <- getInputLine  "Stability   [unstable]: "
+    portab <- getInputLine  "Portability [non-port]: "
+    return $ Configuration (def mod "$Header$")
+                           (def desc "")
+                           (def auth "")
+                           (def copyr copyRightText)
+                           (def lic "MIT")
+                           (def maint "")
+                           (def stab "unstable")
+                           (def portab "non-portable (Portability is untested.)")
+
+initializeDefinition :: IO ()
+initializeDefinition = do
+  conf <- requestConfiguration
+  file <- openFile ".headergen.def" WriteMode
+  BS.hPutStr file (encodePretty conf)
+  hFlush file
+  hClose file
+
+tryCreate :: String -> IO ()
+tryCreate mod = do
+  cwd <- getCurrentDirectory
+  traversePath mod cwd
+
+printHelpMessage :: IO ()
+printHelpMessage = do
+  putStrLn "Usage: [init|create MODULE]"
+  putStrLn ""
+
+-- | The entry point of the application.
+main :: IO ()
+main = do
+  args <- getArgs
+  handleParameters args
+  where
+    handleParameters ["init"]        = initializeDefinition
+    handleParameters ["create", mod] = tryCreate (mod -<.> ".hs")
+    handleParameters _               = printHelpMessage
+