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bug#34852: 26.1; seq-intersection ignores nil as element
From: |
Stefan Monnier |
Subject: |
bug#34852: 26.1; seq-intersection ignores nil as element |
Date: |
Thu, 14 Mar 2019 22:40:27 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
>> > (seq-contains nil '(nil t foo) (lambda (x) t)) -> nil
>> > It returns *nil* if testfn fails, or *nil* (ELT) if it succeds.
>> Just because it sometimes does doesn't mean it always does:
>> (seq-contains '(0 3 4) 1 #'<)
>> returns 3
> Maybe it's too late here, but why is that a counterexample for
>> If ELT=nil, seq-contains currently returns nil anyway;"
Duh, sorry, I lost sight of the goal along the way.
A short real counter example is
(seq-contains '(1) nil #'list)
but it's admittedly contrived. A more real counter example is the one
alluded to by Nicolas earlier:
(seq-contains '((t 1) (nil 2)) nil (lambda (x y) (equal x (car y))))
> The first element is returned for that the test succeeds, what's special
> about it? < is not symmetrical, though, so it's a weird kind of
> equality test.
The test doesn't need to be an equality test.
IOW seq-contains is very close to seq-find.
Stefan
- bug#34852: 26.1; seq-intersection ignores nil as element, (continued)
- bug#34852: 26.1; seq-intersection ignores nil as element, Miguel V. S. Frasson, 2019/03/14
- bug#34852: 26.1; seq-intersection ignores nil as element, Stefan Monnier, 2019/03/14
- bug#34852: 26.1; seq-intersection ignores nil as element, Miguel V. S. Frasson, 2019/03/14
- bug#34852: 26.1; seq-intersection ignores nil as element, Stefan Monnier, 2019/03/14
- bug#34852: 26.1; seq-intersection ignores nil as element, Miguel V. S. Frasson, 2019/03/14
- bug#34852: 26.1; seq-intersection ignores nil as element, Michael Heerdegen, 2019/03/14
- bug#34852: 26.1; seq-intersection ignores nil as element,
Stefan Monnier <=
- bug#34852: 26.1; seq-intersection ignores nil as element, Michael Heerdegen, 2019/03/15
- bug#34852: 26.1; seq-intersection ignores nil as element, Stefan Monnier, 2019/03/15
- bug#34852: 26.1; seq-intersection ignores nil as element, Miguel V. S. Frasson, 2019/03/14
- bug#34852: 26.1; seq-intersection ignores nil as element, Michael Heerdegen, 2019/03/14
- bug#34852: 26.1; seq-intersection ignores nil as element, Basil L. Contovounesios, 2019/03/15
- bug#34852: 26.1; seq-intersection ignores nil as element, Miguel V. S. Frasson, 2019/03/15
- bug#34852: 26.1; seq-intersection ignores nil as element, Miguel V. S. Frasson, 2019/03/16
- bug#34852: 26.1; seq-intersection ignores nil as element, Basil L. Contovounesios, 2019/03/16
- bug#34852: 26.1; seq-intersection ignores nil as element, Miguel V. S. Frasson, 2019/03/16
- bug#34852: 26.1; seq-intersection ignores nil as element, Basil L. Contovounesios, 2019/03/15