Re: sorted?

On Mon, Dec 09, 2024 at 07:14:10PM +0000, Stefan Schmiedl wrote:
> ------ Original Message ------
> > From [email protected]

[...]

> > This seems the intention. But since it accepts an arbitrary "less"
> > function, it ends being iffy. How do you go from some "less" to a
> > "less-or-equal" without running into undecidability dark alleys?
> > 
> Well, the iffyness is managed by the programmer, who chooses the
> comparison function.
> 
> Do you have an example of such an iffy set?

I think Mikael just posted one, in another arm of this thread
(comparing pairs where only the car is relevant, i.e.

  (lambda (p1 p2) (< (car p1) (car p2)))

Then you'd need a corresponding equal, because otherwise you
end up with things which are neither less nor equal nor greater,
i.e. the ordering isn't total, which is bad for sorting :)

Cheers
-- 
t

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