Re: sorted?

[Mikael Djurfeldt]

On Mon, Dec 9, 2024 at 7:59 PM <tomas@tuxteam.de> wrote:

> > (= a b) is equivalent to (not (or (< a b) (> a b)))
>
> Yes, but for that, you have to know what "=" is. Is it eq? Is it
> eqv? Is it equal? (yeah, lame pun with question marks). Or is it
> (see below)?
>

It's equal in the sense of (not (or (< a b) (> a b)). If < is Scheme <
(i.e. comparing numbers), then this is completely equivalent with Scheme =.


> > The reason why you need to pass less to sort is that sort needs a way to
> > determine when an object should go before another one. Let's for example
> > take the example of a list of neuronal spike events. Each event is (TIME
> .
> > ID). It could be unsorted because the data might come from different
> > detectors. To sort the list in time, we would call sort like this:
> >
> > (sort '((0.73 . 7) (0.23 . 3) (0.54 . 17) (0.27 . 98)) (lambda (x y) (<
> > (car x) (car y))))
>
> So here you'd need your equal to be (eq (car x) (car y)), right?
>

As I've tried to convey, you don't need equal when sorting using `sort'.
But the equal corresponding to < is = in Scheme.