seq-mapn and circular lists

seq-mapn and circular lists

[Plamen Tanovski]

Hi,

while cl-map works fine on circular lists, seq-mapn just freezes

(let ((l1 '#1=(1 . #1#)))
  ; (map 'list #'+ '(3 4 5 7) l1)
  (seq-mapn #'+ '(3 4 5 7) l1))

Making the circular list with setcdr or nconc doesn't help. Any
suggestions?

best regards
PT

Re: seq-mapn and circular lists

[John Mastro]

Plamen Tanovski <pgt@arcor.de> wrote:
> Hi,
>
> while cl-map works fine on circular lists, seq-mapn just freezes
>
> (let ((l1 '#1=(1 . #1#)))
>   ; (map 'list #'+ '(3 4 5 7) l1)
>   (seq-mapn #'+ '(3 4 5 7) l1))
>
> Making the circular list with setcdr or nconc doesn't help. Any
> suggestions?

Indeed, seq-map and seq-mapn do not attempt to identify or handle circular
lists. My advice would be to avoid circular lists, or stick to `cl-map' if you
must accommodate them :)

Since seq.el is developed as part of Emacs, you can use `M-x report-emacs-bug'
to submit a feature request.

        John

Re: seq-mapn and circular lists

[Michael Heerdegen]

John Mastro <john.b.mastro@gmail.com> writes:

[CC'ing the author of seq.el, Nicolas]

> > while cl-map works fine on circular lists, seq-mapn just freezes
> >
> > (let ((l1 '#1=(1 . #1#)))
> >   ; (map 'list #'+ '(3 4 5 7) l1)
> >   (seq-mapn #'+ '(3 4 5 7) l1))
> >
> > Making the circular list with setcdr or nconc doesn't help. Any
> > suggestions?

> Indeed, seq-map and seq-mapn do not attempt to identify or handle
> circular lists. My advice would be to avoid circular lists, or stick
> to `cl-map' if you must accommodate them :)

The problem seems to be that `seq-mapn' transforms every argument
sequence into a list before doing anything - but it doesn't check if
anything is already a list, so it effectively copies any list argument,
and this is what makes the thing freeze.  If we avoid this copying, the
function would already do the right thing.

> Since seq.el is developed as part of Emacs, you can use `M-x
> report-emacs-bug' to submit a feature request.

Yes, please do that, Plamen.


Michael.

Re: seq-mapn and circular lists

[Nicolas Petton]

[-- Attachment #1: Type: text/plain, Size: 266 bytes --]

Michael Heerdegen <michael_heerdegen@web.de> writes:

Hi Michael,

>> Since seq.el is developed as part of Emacs, you can use `M-x
>> report-emacs-bug' to submit a feature request.
>
> Yes, please do that, Plamen.

I pushed a fix in master already :-)

Cheers,
Nico

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 472 bytes --]

Re: seq-mapn and circular lists

[Nicolas Petton]

[-- Attachment #1: Type: text/plain, Size: 256 bytes --]

Nicolas Petton <nicolas@petton.fr> writes:

>>> Since seq.el is developed as part of Emacs, you can use `M-x
>>> report-emacs-bug' to submit a feature request.
>>
>> Yes, please do that, Plamen.
>
> I pushed a fix in master already :-)

And in ELPA.

Nico

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 472 bytes --]