Re: What's missing in ELisp that makes people want to use cl-lib?

[João Távora]

On Tue, Nov 14, 2023 at 12:20 PM Dmitry Gutov <dmitry@gutov.dev> wrote:
>
> On 14/11/2023 14:14, João Távora wrote:
> >> The way I understand this, is any new sequence type has to implement
> >> seq-do. As soon as that happens, a lot of (probably all) sequence
> >> functions in seq.el start working on that type.
> > Right.  But seq-difference-3 doesn't call into seq-do anymore,
> > at least not always and not in the same way.  So today,_before_
> > your seq-difference "skips-the-seq-do" optimization, a given person's
> > set difference operations would work just fine for their custom
> > data type.  The person is happy and doesn't care about seq.el's
> > performance.
>
> seq-difference-3 calls seq-filter which calls seq-map, which in turn
> delegates to seq-do

OK, but not always in the same ways as seq-difference did,
and not always in the same way for different predicates.
And and not for sequences of type sequence and list, so if I have
special method on seq-do for my FUNCTION argument, it will
not be called.

João