Re: table.sort: invalid order function for sorting

How so? There is no meaningful difference between "a < b" and "a <= b" 
as convention for a comparator,
because "a <= b" is equivalent to "not (b < a)". It is just a 
convention, and a pretty reasonable one at that.

- Lars


On Sun, Apr 26 2026 at 13:18:38 +02:00:00, Philippe Verdy 
<[email protected]> wrote:
> If you want stability, suitable for mitlkey sort, or sorts in 
> multiple passes, and the minimum of swaps for duplicate values, or 
> for NaN values), using the comparator (a<b) does not work at all, but 
> (a<=b) does.
> 
> Lua made the worst decision for its binary comparator used in 
> table.sort!
> 
> As a conséquence you always need to rewrite it.
> 
> Le ven. 24 avr. 2026, 21:19, 'Martin Eden' via lua-l 
> <[email protected] <mailto:[email protected]>> a écrit :
>> On 2026-04-24 21:13, Roberto Ierusalimschy wrote:
>>  >> [...] Have you ever met the case when you need to code effective
>>  >> sorting in practice?
>>  > I really don't think this information is relevant to this list. 
>> Let us
>>  > avoid allowing arguments to get too personal. Thanks.
>>  >
>>  > -- Roberto
>> 
>>  I agree here. Let's consider it as rhetorical question.
>> 
>>  But I still want to discuss three-way vs two-way partitioning.
>>  Current Lua uses two-way as a given fact. I want to evaluate
>>  alternatives.
>> 
>>  -- Martin
>> 
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