Subject: bug#34852: 26.1; seq-intersection ignores nil as element

From: Nicolas Petton <[email-masked]>
Date: Mon, 18 Mar 2019 12:55:11 +0100

"Basil L. Contovounesios" <[email-masked]> writes:

>> Unless somebody disagrees, I'll install your patch.
>
> If you go with the seq-some patch then please edit it to avoid using
> apply-partially, which is quite inefficient.

Yes, will do.

> The implementations of seq-set-equal-p, seq-uniq, and seq-difference
> will also need to be updated, in addition to that of seq-intersection.

Yes, thank you.

I'm now thinking about introducing a proper predicate to be used instead
of seq-contains for such cases, I would name it `seq-includes-p'.  Here
are my reasons:

- seq-some takes a predicate function, but we'd like a function that
  takes an elt to be tested.

- seq-contains returns the element found on purpose, it is not a
  predicate.  I think it has its use-cases, and I don't want to change
  it into a predicate now (I would have to rename it anyway).

Cheers,
Nico