New EEP draft: Pinning operator ^ in patterns

Raimo Niskanen raimo+erlang-questions@REDACTED
Tue Jan 19 19:38:15 CET 2021

On Tue, Jan 19, 2021 at 06:54:14PM +0100, Nicolas Martyanoff wrote:
> On 2021-01-19 18:15, Raimo Niskanen wrote:
> > And, as others have pointed out.  We need to know the direction; is this
> > where are we heading towards?  I think that this change in itself just may
> > be worth its own weight, but possible future changes are more interesting.
> In the spirit of elevating the debate beyond the discussion around the pinning
> proposition, and to echo the question which was asked earlier about "the
> intent and larger picture of this change", I would really like to who are "we"
> in your message, and where are this "future changes" coming from.

Yes.  Of course.

By "we" I ment the community, including us at the Erlang/OTP team at Ericsson
that will have to decide on this EEP.

With "future changes" I ment for example the scoping rules that, again, has
been brought up in this discussion, such as exporting from case/if/begin
block, and importing variables into fun()s from the surrounding scope.  But
also if this would be intended to be a first step towards variable
rebinding (which would be too much towards Elixir according to me).

It seems the WhatsApp team have a lot of ideas, and Elixir is also an
influence nowdays.

So if the people behind this EEP has got a bigger agenda it would be nice to
know about it before deciding on this one.  Maybe the ^ character could be
put to better use if the community and Ericsson should not fancy that

> There has been mention of the WhatsApp team, but unless I am mistaken, neither
> Richard nor you work for WhatsApp (and as far as I know, Facebook/WhatsApp do
> not have any special authority on the evolution of Erlang). I do not know who
> at Ericsson is in charge of the language itself, but it does not seem they are
> part of this discussion.

Some right and wrong guesses there. :-)

Richard has apparently collaborated with the WhatsApp team since this EEP
was presented as coming from "Richard & the good folks at WhatsApp".
As you say WhatsApp has no special authority on the evolution of Erlang,
other than being recognized for having lots of user experience and

I work in the Erlang/OTP team at Ericsson, which can be seen from my mail
footer.  The others in the team are lurking, watching the show, munching on
popcorn, I guess.  We have had some internal coffee time discussions, but most
keep indoors to avoid the storm.

> Apparently some people have plans to change the language in significant ways
> (there has been talks about scoping rules!). Of course everyone is free to
> submit propositions to Ericsson, even when these propositions are impopular,
> but I am not sure the discussion is productive without the active involvement
> of the people in charge.

I agree that it might be good if some more people from the Erlang/OTP team
participated in the discussion.  Although the Community's points of view is
visible through just observing the discussion.  There are many language
knowledgeble people on this list that does not work at Ericsson, and we
value their opinions.

In hindsight I get a feeling that things that we think are obvious, such as
how carefully and step-wise we introduce changes, when we introduce them,
could have been stated early in this discussion, and thus maybe avoided
some backwards compatibility panic...

> -- 
> Nicolas Martyanoff
> khaelin@REDACTED


/ Raimo Niskanen, Erlang/OTP, Ericsson AB

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