Solve 542f3d5fd002f86efc00081a

src/Kyu6/PrimeFactors.hs

@@ -0,0 +1,6 @@
+module Kyu6.PrimeFactors where
+
+primeFactors :: Integer -> [Integer]
+primeFactors n =
+  let f = head [x | x <- [2 .. n], n `mod` x == 0]
+   in if n == 1 then [] else f : primeFactors (n `div` f)

test/Kyu6/PrimeFactorsSpec.hs

@@ -0,0 +1,14 @@
+module Kyu6.PrimeFactorsSpec (spec) where
+
+import Kyu6.PrimeFactors (primeFactors)
+import Test.Hspec
+
+spec :: Spec
+spec = do
+  describe "Prime factors" $ do
+    it "Example tests" $ do
+      primeFactors 1 `shouldBe` []
+      primeFactors 3 `shouldBe` [3]
+      primeFactors 8 `shouldBe` [2, 2, 2]
+      primeFactors 9 `shouldBe` [3, 3]
+      primeFactors 12 `shouldBe` [2, 2, 3]