I once had occasion to implement a sort algorithm in anger, on a platform _with_ a standard library no less! The project was written in SmallTalk, running on a

I once had occasion to implement a sort algorithm in anger, on a platform _with_ a standard library no less! The project was written in SmallTalk, running on a very old implementation (last updated in 1999 I think) and we had a problem where clicking on column headers in the UI to sort would be very slow if most of the values were equal. The problem was that the standard library array sort was quicksort (which also meant that sorting on several columns broke since quicksort isn't stable), but since SmallTalk makes these things possible when you need to replacing the stdlib quicksort with mergesort was actually a fairly simple operation.