diff --git a/haskell/e009.hs b/haskell/e009.hs
index 4e6e157..7d8af99 100644
--- a/haskell/e009.hs
+++ b/haskell/e009.hs
@@ -10,18 +10,29 @@ Find the product abc.
 
 import Text.Printf
 
+-- |A triangle consisting of three integral sides
+data Triangle = Triangle Int Int Int
+
+-- |Return the product of the sides of the first triangle having the sum of the sides 'sum'
+triplet :: Int -> Int
 triplet sum = do
     let cs = reverse (takeWhile (<= sum - 3) [3,5..])
-    let tri = head (concat (map (\x -> diffs sum x) cs))
-    let (a, b, c) = tri
+    let tri = head (concat (map (\x -> right_triangles sum x) cs))
+    let (Triangle a b c) = tri
     a * b * c
-diffs sum c = do
+
+-- |Find all right triangles having sum of sides 'sum' and side c length of 'c'
+right_triangles :: Int -> Int -> [Triangle]
+right_triangles sum c = do
     let diff = sum - c
     let range = [1..(floor ((fromIntegral diff) / 2)) + 1]
-    let triangles = filter is_triangle (map (\x -> (x, diff - x, c)) range)
+    let triangles = filter is_right_triangle (map (\x -> Triangle x (diff - x) c) range)
     triangles
-is_triangle (a, b, c) =
+
+-- |Return whether the provided triangle is a right triangle using the pythagorean theorem
+is_right_triangle :: Triangle -> Bool
+is_right_triangle (Triangle a b c) =
     a^2 + b^2 == c^2
 
 main = do
-    printf "Pythagorean triplet product having a + b + c = 1000: %d\n" (triplet 1000 :: Integer)
+    printf "Pythagorean triplet product having a + b + c = 1000: %d\n" (triplet 1000 :: Int)