On Tue, Mar 11, 2008 at 4:01 AM, Adrian Hey <[EMAIL PROTECTED]> wrote:
> > and sorting is
> > meant to be a permutation, so we happily have the situation where this
> > has a correct answer: 2.
>
> > Anything else is incorrect.
>
> Isn't 3 also a permutation? Why is it incorrect?
Because it is not stable.
The documentation for Data.List.sort says the sort is stable:
"The sort function implements a stable sorting algorithm."
A stable sort respects the order of equal elements as they occur in
the input list.
--
Denis
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