On Sat, 8 Apr 2017, Philipp Stephani wrote:
>
>
> Tino Calancha <tino.calancha@gmail.com> schrieb am Sa., 8. Apr. 2017 um 06:46 Uhr:
>
>
> On Fri, 7 Apr 2017, Drew Adams wrote:
>
> >>> Or an addition to cl-loop that would allow doing something like
> >>>
> >>> (cl-loop for m being the matches of "foo\\|bar"
> >>> do ...)
> >>>
> >>> Then you could easily 'collect m' to get the list of matches if you want
> >>> that.
> >>
> >> Your proposals looks nice to me ;-)
> >
> > (Caveat: I have not been following this thread.)
> >
> > I think that `cl-loop' should be as close to Common Lisp `loop'
> > as we can reasonably make it. We should _not_ be adding other
> > features to it or changing its behavior away from what it is
> > supposedly emulating.
> >
> > If you want, create a _different_ macro that is Emacs-specific,
> > with whatever behavior you want. Call it whatever you want
> > that will not be confused with Common Lisp emulation.
> >
> > Please keep `cl-' for Common Lisp emulation. We've already
> > seen more than enough tampering with this - people adding
> > their favorite thing to the `cl-' namespace. Not good.
> Drew, i respect your opinion; but so far the change
> would just extend `cl-loop' which as you noticed has being already
> extended before.
> For instance, we have:
> cl-loop for x being the overlays/buffers ...
>
> Don't see a problem to have those things.
>
>
> I do. They couple the idea of an iterable with a looping construct, and such coupling is bad for various reasons:
> - Coupling of unrelated entities is always an antipattern.
> - For N iterables and M looping constructs, you need to implement N*M integrations.
> Instead this should use an iterable, e.g. a generator function (iter-defun). cl-loop supports these out of the box.
Then, you don't like (as Drew, but for different reasons) that we have:
cl-loop for x being the buffers ...
I don't like it, but it's there and cannot be removed for compatibility reasons, so I'm not arguing about it. I'm arguing against adding more such one-off forms.
but it seems you are fine having iter-by clause in cl-loop, which seems an
Emacs extension (correctme if i am wrong). So in principle, you are happy
with adding useful extensions to CL, not just keep it an emulation as
Drew wants.
Yes, I don't care about Common Lisp. The iter-by clause is less of a problem than 'buffers' etc. because it's not a one-off that couples a looping construct with some random semantics.
Your point is about performance.
No, I care mostly about clarity, simplicity, and good API design, including separation of concerns.
I am driven by easy to write code.
Maybe you can provide an example about how to write those things using
the iter-by cl-loop clause.
Sure:
(require 'generator)
(iter-defun re-matches (regexp)
(while (re-search-forward regexp nil t)
(iter-yield (match-string 0))))
(iter-do (m (re-matches (rx digit)))
(print m))
(cl-loop for m iter-by (re-matches (rx digit))
do (print m))