Solve 'Array - squareUp b!' kata

Author: borisskert

src/ArraySquareUp.hs

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+module ArraySquareUp (squareUp) where
+
+-- https://www.codewars.com/kata/5a8bcd980025e99381000099/train/haskell
+
+squareUp :: Int -> [Int]
+squareUp n = concatMap (pattern' n) $ [1 .. n]
+
+pattern' :: Int -> Int -> [Int]
+pattern' size n
+  | n == 1 = padding ++ [1]
+  | otherwise = padding ++ [n, n - 1 .. 1]
+  where
+    padding = replicate (size - n) 0

test/ArraySquareUpSpec.hs

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+module ArraySquareUpSpec (spec) where
+
+import ArraySquareUp (squareUp)
+import Test.HUnit (assertEqual)
+import Test.Hspec
+
+spec :: Spec
+spec = do
+  it "example tests" $ do
+    assertEqual "squareUp 2" [0, 1, 2, 1] $ squareUp 2
+    assertEqual "squareUp 3" [0, 0, 1, 0, 2, 1, 3, 2, 1] $ squareUp 3
+    assertEqual "squareUp 4" [0, 0, 0, 1, 0, 0, 2, 1, 0, 3, 2, 1, 4, 3, 2, 1] $ squareUp 4