Solve 'Will there be enough space?' kata

Author: borisskert

src/Bus.hs

@@ -0,0 +1,10 @@
+module Bus (enough) where
+
+-- https://www.codewars.com/kata/5875b200d520904a04000003/train/haskell
+
+enough :: Int -> Int -> Int -> Int
+enough cap on wait
+  | diff < 0 = abs diff
+  | otherwise = 0
+  where
+    diff = cap - on - wait

test/BusSpec.hs

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+module BusSpec where
+
+import Test.Hspec
+import Bus (enough)
+
+spec :: Spec
+spec = do
+  describe "Fixed Tests" $ do
+    mapM_ (\(c@(Case cap on wait), ans) -> it (show c) $ enough cap on wait `shouldBe` ans)
+      [ (Case 10 5 5, 0)
+      , (Case 100 60 50, 10)
+      , (Case 20 5 5, 0)
+      ]
+      
+data Case = Case Int Int Int
+
+instance Show Case where
+  show (Case cap on wait) =
+    "cap: " ++ show cap ++ ", " ++
+    "on: "  ++ show on  ++ ", " ++
+    "wait: " ++ show wait