diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,30 +1,29 @@
-Copyright Suzumiya (c) 2017
+BSD 3-Clause License
 
+Copyright (c) 2017, suzumiyasmith
 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 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.
+* 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 Suzumiya nor the names of other
-      contributors may be used to endorse or promote products derived
-      from this software without specific prior written permission.
+* Neither the name of the copyright holder nor the names of its
+  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
+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 HOLDER 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/light.cabal b/light.cabal
--- a/light.cabal
+++ b/light.cabal
@@ -1,5 +1,5 @@
 name:                light
-version:             0.1.0.0
+version:             0.2.0.0
 synopsis:            a simple physics engine
 description:         A simple physics engine(dynamics only) with collision dection
 homepage:            https://github.com/suzumiyasmith/light#readme
@@ -15,6 +15,7 @@
 
 library
   hs-source-dirs:      src
+  ghc-options:         -Wall
   exposed-modules:     Physics.Light
   build-depends:       base >= 4.7 && < 5
                      , linear >= 1.20 && < 2
diff --git a/src/Physics/Light.hs b/src/Physics/Light.hs
--- a/src/Physics/Light.hs
+++ b/src/Physics/Light.hs
@@ -4,7 +4,6 @@
 
 import GJK
 
-import Control.Arrow
 import Control.Lens
 import Control.Monad.Writer.Lazy
 import Data.Fixed
@@ -37,8 +36,8 @@
 addObjects (o:os) w = addObjects os $ addObject o w
 addObjects [] w = w
 
-update :: Double -> PhysicsWorld -> PhysicsWorld
-update dt = first (fmap w)
+update :: Double -> IM.IntMap Object2D -> IM.IntMap Object2D
+update dt = fmap w
   where
     w :: Object2D -> Object2D
     w o = o
@@ -46,8 +45,8 @@
       & velocity %~ (+ o ^. acceleration ^* dt)
       & position .  _z %~ (`mod'` (2 * pi))
 
-detectCollision :: PhysicsWorld -> [(Int, Int)]
-detectCollision (w, _) =
+detectCollision :: IM.IntMap Object2D -> [(Int, Int)]
+detectCollision w =
   execWriter $ IM.traverseWithKey (\k o -> tell $ fmap ((,) k) (detect w k o)) w
 
 detect :: IM.IntMap Object2D -> Int -> Object2D -> [Int]
diff --git a/test/Spec.hs b/test/Spec.hs
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -1,11 +1,12 @@
 import Control.Lens
+import Control.Arrow
 import qualified Data.IntMap.Lazy as IM
 import Linear
 import Physics.Light
 
 main :: IO ()
 main = do
-  print $ detectCollision <$> (updateTest <$> [1 .. 1000] <*> [testWorld1, testWorld2])
+  print $ (detectCollision . fst) <$> (updateTest <$> [1 .. 1000] <*> [testWorld1, testWorld2])
 
 testShape1 = [circle 1, ellipse 0.5 3]
 
@@ -25,4 +26,4 @@
 
 updateTest :: Int -> PhysicsWorld -> PhysicsWorld
 updateTest 0 w = w
-updateTest n w = update 0.1 $ updateTest (n - 1) w
+updateTest n w = first (update 0.1) $ updateTest (n - 1) w