unstableSort +containers

unstableSort :: Ord a => Seq a -> Seq a
containers Data.Sequence
O(n log n). unstableSort sorts the specified Seq by the natural ordering of its elements, but the sort is not stable. This algorithm is frequently faster and uses less memory than sort, and performs extremely well -- frequently twice as fast as sort -- when the sequence is already nearly sorted.
unstableSortBy :: (a -> a -> Ordering) -> Seq a -> Seq a
containers Data.Sequence
O(n log n). A generalization of unstableSort, unstableSortBy takes an arbitrary comparator and sorts the specified sequence. The sort is not stable. This algorithm is frequently faster and uses less memory than sortBy, and performs extremely well -- frequently twice as fast as sortBy -- when the sequence is already nearly sorted.