>>> sortBy (comparing fst) (select [(1,'a'),(4,'b'),(2,'c'),(3,'d'),(3,'e'),(7,'f')]) [(1,'a'),(2,'c'),(3,'d'),(3,'e'),(4,'b'),(7,'f')]
>>> sortBy cmp = StreamK.mergeMapWith (StreamK.mergeBy cmp) StreamK.fromPureHowever, this combinator uses a parser to first split the input stream into down and up sorted segments and then merges them to optimize sorting when pre-sorted sequences exist in the input stream. O(n) space