Tango lacks a stable sort

Thanks. I'd planned on adding a stable sort routine but wasn't sure of the best algorithm to use so I put it off and forgot about it. Merge sort is a decent option, though, so perhaps I'll use that. It presents a good opportunity to offer merge sort anyway, which some people may want to use instead of the in-place sort routine in some instances. I'll admit that was one reason I offered the heap routines as well--they provide heap sort "for free."

Merge sort is generally considered the fastest stable sort there is. (Or at least, I haven't come across anything which even claims to be faster whilst preserving stability.)

The problem with it is that it uses O(n) storage, because it needs to merge the data into a temporary array. There are in-place merge sorts, but they're noticeably slower than the ones which use the storage, and notoriously harder to code.

It's up to you: as usual, I prefer the most general approach, which is to provide both in-place merge sort (the default stable sort) and merge sort taking an additional buffer argument. If the buffer is too small, it is resized to the length of the array being sorted.

One implementation of in-place merge sort can be found here: http://thomas.baudel.name/Visualisation/VisuTri/inplacestablesort.html

Wanna update your stable-sort and add it in the appropriate place, Deewiant?