Solve 'Help the farmer to count rabbits, chickens and cows' kata

Author: borisskert

src/Farmer.hs

@@ -0,0 +1,12 @@
+module Farmer where
+
+import Preloaded (AnimalCount (..))
+
+-- https://www.codewars.com/kata/5a02037ac374cbab41000089/train/haskell
+
+getAnimalsCount :: Int -> Int -> Int -> AnimalCount
+getAnimalsCount legs heads horns = AnimalCount rabbits chickens cows
+  where
+    cows = horns `div` 2
+    chickens = 2 * heads - legs `div` 2
+    rabbits = heads - cows - chickens

src/Preloaded.hs

@@ -49,3 +49,10 @@ animals = ["Rat", "Ox", "Tiger", "Rabbit", "Dragon", "Snake", "Horse", "Goat", "
 elements = ["Wood", "Fire", "Earth", "Metal", "Water"]
 
 data Colour = White | Black deriving (Show, Eq, Ord, Enum, Bounded)
+
+data AnimalCount = AnimalCount
+  { rabbits :: Int,
+    chickens :: Int,
+    cows :: Int
+  }
+  deriving (Show, Eq)

test/FarmerSpec.hs

@@ -0,0 +1,14 @@
+module FarmerSpec where
+
+import Test.Hspec
+import Test.HUnit
+import Farmer (getAnimalsCount)
+import Preloaded
+
+spec :: Spec
+spec = do
+  it "Fixed Tests" $ do
+    assertEqual "getAnimalsCount 34 11 6" (AnimalCount 3 5 3) $
+      getAnimalsCount 34 11 6
+    assertEqual "getAnimalsCount 154 42 10" (AnimalCount 30 7 5) $
+      getAnimalsCount 154 42 10