diff --git a/src/Lib.hs b/src/Lib.hs
index aacd2ec..a2a63b3 100644
--- a/src/Lib.hs
+++ b/src/Lib.hs
@@ -1,12 +1,23 @@
+{-|
+Module      : Lib
+Description : N-body simulation
+Copyright   : (c) Dimitri Lozeve, 2017
+License     : BSD3
+Maintainer  : dimitri.lozeve@gmail.com
+-}
 module Lib (
+  -- * Constants
   gravity,
+  -- * Body type
   Body(..),
   bodyDistance,
+  -- * Gravity force
   field,
   acceleration,
+  -- * Simulation
   update,
   updateAll,
-  b1, b2, b3,
+  -- * Examples
   au, sun, earth, moon, mercury, venus, mars
   ) where
 
@@ -19,7 +30,7 @@ import Linear.Metric
 -- CONSTANTS
 --------------------------------------------------------------------------------
 
--- Gravitational constant [m^3 kg^-1 s^-2]
+-- | Gravitational constant [m^3 kg^-1 s^-2]
 gravity :: Double
 gravity = 6.67408e-11
 
@@ -27,17 +38,17 @@ gravity = 6.67408e-11
 -- BODY TYPE
 --------------------------------------------------------------------------------
 
--- Body
+-- | Body type
 data Body = Body {
-  bodyName :: String,
-  bodyRadius :: Double, -- [m]
-  bodyMass :: Double, -- [kg]
-  bodyPosition :: Point V3 Double, -- [m]
-  bodySpeed :: V3 Double -- [m/s]
+  bodyName :: String, -- ^ Name
+  bodyRadius :: Double, -- ^ Radius [m]
+  bodyMass :: Double, -- ^ Mass [kg]
+  bodyPosition :: Point V3 Double, -- ^ Position [m]
+  bodySpeed :: V3 Double -- ^ Speed [m/s]
   } deriving (Show, Eq)
 
 
--- Distance between two bodies
+-- | Distance between two bodies
 bodyDistance :: Body -> Body -> Double
 bodyDistance body1 body2 =
   distance (bodyPosition body1) (bodyPosition body2)
@@ -47,7 +58,7 @@ bodyDistance body1 body2 =
 -- GRAVITY FORCE
 --------------------------------------------------------------------------------
 
--- Field created by a body on a certain position
+-- | Field created by a body on a certain position
 field :: Body -> Point V3 Double -> V3 Double
 field body pos =
   unP $ (gravity * m / r**2) *^ normalize vec
@@ -55,7 +66,7 @@ field body pos =
         vec = bodyPosition body - pos
         r = norm vec
 
--- Acceleration given to a body by its neighbours
+-- | Acceleration given to a body by its neighbours
 acceleration :: Body -> [Body] -> V3 Double
 acceleration body = foldr f 0
   where f neighbour acc =
@@ -66,15 +77,18 @@ acceleration body = foldr f 0
 -- SIMULATION
 --------------------------------------------------------------------------------
 
--- Update speed and position with using a timestep dt
-update :: Double -> Body -> [Body] -> Body
+-- | Update speed and position
+update :: Double -- ^ The time step
+  -> Body -- ^ The body to update
+  -> [Body] -- ^ The Body's neighbours
+  -> Body -- ^ The updated Body
 update dt (Body name r m pos speed) neighbours =
   Body name r m newpos newspeed
   where accel = acceleration (Body name r m pos speed) neighbours
         newspeed = speed + dt *^ accel
         newpos = pos + dt *^ P newspeed
 
--- Update all bodies with a timestep dt
+-- | Update all bodies with a timestep dt
 updateAll :: Double -> [Body] -> [Body]
 updateAll dt = aux [] []
   where
@@ -89,17 +103,19 @@ updateAll dt = aux [] []
 -- EXAMPLES
 --------------------------------------------------------------------------------
 
-b1 = Body "b1" 1 42e12 (P $ V3 0 0 0) (V3 0 0 0)
-b2 = Body "b2" 1 11e12 (P $ V3 1 2 3) (V3 0 3e3 0)
-b3 = Body "b3" 1 5e12 (P $ V3 5 2 1) (V3 3e3 1e3 0)
-
--- Astronomical Unit [m]
+-- | Astronomical Unit [m]
 au :: Double
 au = 149597870700
 
+-- | The Sun
 sun  = Body "Sun" 695700000 1.98855e30 (P $ V3 0 0 0) (V3 0 0 0)
+-- | The Earth
 earth = Body "Earth" 6.371e6  8.97237e24 (P $ V3 au 0 0) (V3 0 29.78e3 0)
+-- | The Moon
 moon = Body "Moon" 1.7371e6 7.342e22 (P $ V3 (au+384399e3) 0 0) (V3 0 (29.78e3+1022) 0)
+-- | Mercury
 mercury = Body "Mercury" 2.4397e6 3.3011e23 (P $ V3 57909050000 0 0) (V3 0 47362 0)
+-- | Venus
 venus = Body "Venus" 6.0518e6 4.8675e24 (P $ V3 108208000000 0 0) (V3 0 35.02e3 0)
+-- | Mars
 mars = Body "Mars" 3.3895e6 6.4171e23 (P $ V3 227.9392e9 0 0) (V3 0 24.077e3 0)