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bug#34852: 26.1; seq-intersection ignores nil as element
From: |
Michael Heerdegen |
Subject: |
bug#34852: 26.1; seq-intersection ignores nil as element |
Date: |
Thu, 14 Mar 2019 14:09:15 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
"Basil L. Contovounesios" <contovob@tcd.ie> writes:
> One solution is to leave seq-contains as it is, and switch to using
> seq-position (or some new predicate) as a predicate instead. Another is
> to make seq-contains return a boolean instead of the needle found, which
> would be a backward-incompatible change similar to that for
> map-contains-key. I attach a patch for each of these respective
> solutions; WDYT?
We also have `seq-some' which can be used as a contain predicate,
e.g. to fix this bug:
From c53a80c29e696ab64d4279ca6f495c8e0e1b16b4 Mon Sep 17 00:00:00 2001
From: Michael Heerdegen <michael_heerdegen@web.de>
Date: Thu, 14 Mar 2019 13:55:41 +0100
Subject: [PATCH] Fix seq-intersection with nil
---
lisp/emacs-lisp/seq.el | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/lisp/emacs-lisp/seq.el b/lisp/emacs-lisp/seq.el
index 4a811d7895..5718343a8f 100644
--- a/lisp/emacs-lisp/seq.el
+++ b/lisp/emacs-lisp/seq.el
@@ -409,12 +409,13 @@ seq-sort-by
(cl-defgeneric seq-intersection (sequence1 sequence2 &optional testfn)
"Return a list of the elements that appear in both SEQUENCE1 and SEQUENCE2.
Equality is defined by TESTFN if non-nil or by `equal' if nil."
- (seq-reduce (lambda (acc elt)
- (if (seq-contains sequence2 elt testfn)
- (cons elt acc)
- acc))
- (seq-reverse sequence1)
- '()))
+ (let ((testfn (or testfn #'equal)))
+ (seq-reduce (lambda (acc elt)
+ (if (seq-some (apply-partially testfn elt) sequence2)
+ (cons elt acc)
+ acc))
+ (seq-reverse sequence1)
+ '())))
(cl-defgeneric seq-difference (sequence1 sequence2 &optional testfn)
"Return a list of the elements that appear in SEQUENCE1 but not in SEQUENCE2.
--
2.20.1
(probably needed in more places as you did in one of your patches)
So I think we don't necessarily need something new or a backward
incompatible change.
Michael.
- bug#34852: 26.1; seq-intersection ignores nil as element, Miguel V. S. Frasson, 2019/03/13
- 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, 2019/03/14
- 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, 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