>>> nub [1,2,3,4,3,2,1,2,4,3,5] [1,2,3,4,5]If the order of outputs does not matter and there exists instance Ord a, it's faster to use map Data.List.NonEmpty.head . Data.List.NonEmpty.group . sort, which takes only <math> time.
>>> nub (fromList [1,1,2,6,6]) fromList [1,2,6]
>>> nub $ replicate 5 'a' Slist {sList = "a", sSize = Size 1} >>> nub mempty Slist {sList = [], sSize = Size 0} >>> nub $ slist [1,2,3,4,3,2,1,2,4,3,5] Slist {sList = [1,2,3,4,5], sSize = Size 5}