Formal comment #142 (enhancement)

Change the response to formal comment #47 to provide vector-sort!, not vector-sort.
Reported by: 	John Cowan
Version:	5.92

Report version: 5.92

The response to formal comment #47 says that R6RS will provide
list-sort and vector-sort procedures, both to be stable and
nondestructive. However, an important application of vectors is in
situations where large sequences are required and memory must be
conserved. In this context, it is often useful to sort a 1G vector in
place rather than causing the application to thrash (or crash) by
allocating another such vector.

Providing vector-sort! as primitive will alleviate this
requirement. It is very easy to define vector-sort on top of it by
copying the source vector and destructively sorting the copy.

No such issues arise for list-sort, so it can and should be left
nondestructive.


RESPONSE:

In the next draft, `vector-sort!' will be added as a third sorting
primitive.  Its specification will allow it to use algorithms such as
randomized quicksort (unstable, with O(n^2) time in the worst case),
while continuing to require `vector-sort' and `list-sort' to perform
an O(n lg n) stable sort.