fix name shadowing causing type error

Author: chessai

test/ArrayFire/ArithSpec.hs

@@ -98,9 +98,9 @@ shouldBeEps :: Array Double -> Array Double -> Expectation
 actual `shouldBeEps` expected = expect err_msg (cmpEps actual expected)
   where
     err_msg = "expected: " ++ show expected ++ "\n but got: " ++ show actual
-    cmpEps x y =
+    cmpEps a b =
       let x :: Double
-          x = fromIntegral $ Prelude.abs $ x - y
+          x = fromIntegral $ Prelude.abs $ a - b
       in x <= 1e-14
 
 expect :: String -> Bool -> Expectation