Re: Generic sequences in seq.el

[Yuan Fu <casouri@gmail.com>]

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>   (seq-concatenate 'list (seq-subseq seq 0 n)
>                          (list element)
>                          (seq-subseq seq n))

That returns a list, not the sequence. So inserting something into the
sequence
makes it not a sequence anymore?

> We currently don't have any data-structure that can be efficiently
> modified in-place via push/pop (note that even lists don't qualify
> because push/pop doesn't modify the list in place: they replace a list
> with another without modifying any existing list (unless the PLACE is
> the car/cdr of a list, of course, but that's a separate issue)).

Thanks, it's good to know.

Yuan.

On Fri, Dec 21, 2018 at 9:24 AM Stefan Monnier <monnier@iro.umontreal.ca>
wrote:

> >     (setf (nthcdr n seq) (cons element (nthcdr n seq)))
> > to insert element into the nth position in seq
>
> I think with `seq` you'd do something like
>
>    (seq-concatenate 'list (seq-subseq seq 0 n)
>                           (list element)
>                           (seq-subseq seq n))
>
> Of course, it's different because it's non-destructive, but insertion
> into an array can't be done non-destructively anyway.
>
> > The idea is I'll implement this function for the generic sequence
> > that I'll define in the future. Is that a correct approach?
> > Other destructive functions that I couldn't find alternatives are delete,
> > push, pop, etc.
>
> We currently don't have any data-structure that can be efficiently
> modified in-place via push/pop (note that even lists don't qualify
> because push/pop doesn't modify the list in place: they replace a list
> with another without modifying any existing list (unless the PLACE is
> the car/cdr of a list, of course, but that's a separate issue)).
>
>
>         Stefan
>
>
>

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