diff --git a/src/GraphType.hs b/src/GraphType.hs
index db5d990..d17bb5a 100644
--- a/src/GraphType.hs
+++ b/src/GraphType.hs
@@ -1,6 +1,7 @@
 module Main where
 
 import Parse (parseFiles)
+import OptionParser
 
 import Language.Haskell.Exts
 import Data.Generics.PlateData (universeBi)
@@ -9,23 +10,15 @@ import Data.List
 import Data.Maybe
 import Control.Monad
 
--- | Drawing depth
-data Depth = Inf | Limit Int
-
--- TODO:
--- * Add CL options for:
--- ** Specifying input file(s)
--- ** Specifying drawing depth
--- ** Specifying root ADT
--- ** Output file name
 main = do
-  let files = [ "../example/Test01.hs", "../example/Test02.hs" ]
+  (Mode depth output, root, files) <- getOpts
   types <- parseFiles files
-  let graph = buildGraph types Inf "Organization"
-  writeFile "output.dot" graph
+  let graph = buildGraph types depth root
+  writeFile output graph
 
 -- | Builds dependency graph starting with datatype declaration `root'.
 -- Recursively expands all user-defined `types' referenced from `root', up to `depth'
+-- TODO: use depth
 buildGraph types depth root = 
   showDot $ do
     -- Allow links that end on cluster boundaries
diff --git a/src/OptionParser.hs b/src/OptionParser.hs
new file mode 100644
index 0000000..b972c51
--- /dev/null
+++ b/src/OptionParser.hs
@@ -0,0 +1,45 @@
+module OptionParser
+  (
+   Mode(..),
+   getOpts,
+  )
+where
+
+import System (getArgs)    
+import System.Exit
+import System.Console.GetOpt
+import Data.Maybe ( fromMaybe )
+import Control.Monad (when)
+
+data Flag 
+     = Inf | Limit Int | Output FilePath | Help
+       deriving (Eq,Show)
+
+options :: [OptDescr Flag]
+options =
+  [ Option ['d']        ["depth"]   (OptArg getDepth "N") "Follow links up to this depth (default: infinite)",
+    Option ['o']        ["output"]  (OptArg getOutput "file") "Name of the output file (default: output.dot)",
+    Option []           ["help"]    (NoArg Help)    "Show this help" ]
+
+getDepth Nothing = Inf
+getDepth (Just s) = Limit ( read s )
+
+getOutput Nothing = Output "output.dot"
+getOutput (Just s) = Output s
+
+data Mode = Mode { depth :: Maybe Int, output :: String }
+defaultMode = Mode Nothing "output.dot"
+
+update Inf        m = m { depth = Nothing }
+update (Limit n)  m = m { depth = Just n }
+update (Output f) m = m { output = f }
+
+getOpts :: IO (Mode, String, [FilePath])
+getOpts = getArgs >>= \argv ->
+  case getOpt Permute options argv of
+       (o, (root:files), []  ) -> do when (Help `elem` o) (do putStrLn usage 
+                                                              exitWith ExitSuccess)
+                                     return (foldr update defaultMode o, root, files)
+       (_, _, errs)      -> ioError (userError (concat errs ++ usage))
+ where header = "Usage: graphtype [OPTION...] type_name file1.hs file2.hs ..."
+       usage  = usageInfo header options