opCmp, [partial/total/pre]orders, custom floating point types etc.

[John Colvin via Digitalmars-d]

On Tuesday, 12 January 2016 at 19:50:57 UTC, Fool wrote:
> On Tuesday, 12 January 2016 at 19:48:35 UTC, Fool wrote:
>> On Tuesday, 12 January 2016 at 19:46:47 UTC, John Colvin wrote:
>>> On Tuesday, 12 January 2016 at 19:44:18 UTC, Fool wrote:
>>>> Non-reflexive '<=' does not make any sense at all.
>>>
>>> It might be a bit of a mess, agreed, but nonetheless:
>>>
>>> assert(!(float.nan <= float.nan));
>>
>> Agreed, but in case of float '<=' is not an order at all.
>
> By the way, that implies that the result of sorting an array of 
> float by default comparison is undefined unless the array does 
> not contain NaN.

Didn't think of that. Yikes. Should we change the default 
predicate of std.algorithm.sort to std.math.cmp when 
ElementType!R is floating point?