[Haskell-beginners] Inventing QuickCheck properties

Hi, I'm writing QuickCheck properties for the swipeLeft function in a game of 2048. I could think of 3 very basic properties so far and I'm wondering if you guys can think of any other interesting ones. Here are mine: - Verify That It Makes The Number Of Zeroes Go Up (applies "length . (filter (==0))" to both input and output and then does a <= comparison) - Verify That It Cleanly Separates Zeroes To The Right-Hand Side (applies "all (==0) . snd . break (==0)" to the output) - Verify that It Preserves The SumTotal (assert that the sum of all integers is left unchanged) -Dan