New EEP draft: Pinning operator ^ in patterns

[Raimo Niskanen]

Thank you!  Well put!
/ Raimo


On Tue, Jan 19, 2021 at 12:56:01PM +0000, Karl Velicka wrote:
> Dear list,
> 
> I'm not bringing much in way of hard technical arguments, but I'd like to
> share some thoughts about the proposal and community's reaction to it - I
> hope that they will help steer the discussion in a more productive
> direction, similar to what Raimo is trying to do here. I must say that it's
> somewhat upsetting that posts like his or mine are even needed, one would
> expect a lot more tact and and level-headed discussion to be shown in this
> list...
> 
> (FWIW, I had a fiery initial reaction to this myself, but luckily I chose
> not to type anything at the time, as my opposition to the proposal has been
> dwindling the more I think/read about it)
> 
> There's been people describing the operator as "fly-droppings" and similar.
> Firstly, this comes across as an intentionally derogatory name, which makes
> me think that responders using such language are not looking to discuss in
> good faith from the get-go. Secondly, what exactly makes ^Pattern "fly
> droppings" but `foo(<<H:8, _:H>> = X) -> X.` is presumably perfectly
> readable? I think this is largely (if not entirely) down to familiarity.
> Let's not conflate those two things, and let's not pretend like adding
> another glyph to our arsenal is somehow going to make everyone's brain
> explode. I like language cleanliness as much as the next person, but there
> is no need whatsoever to reach for strawmans about 5-char-wide walruses
> that are obviously coming to eat us all.
> 
> Next up, a lot of people are arguing about the syntax more than the feature
> - to those I'd say "do you think the feature is useful/valuable aside from
> syntactic implications?" If so, syntax can perhaps be revised. If not, I'd
> encourage arguing about the semantics of the feature and leave syntactic
> quibbles aside. FWIW, there have been some good discussion there, say re:
> scoping rules.
> 
> In addition, I feel like there's been a certain lack of forthcomingness
> from Richard and/or the WhatsApp team (certainly in the initial post at
> least) about the intent and larger picture of this change - there has been
> a mention in this thread about the possibility of eventually making the
> operator mandatory etc but none of that is in the proposal and I really
> think it should be. I think it may be easier to sell the community on the
> direction Whatsapp believes Erlang should be heading in rather than being
> drop-fed certain aspects/features of it in isolation.
> 
> Lastly, I wonder if there's some "ulterior" motive here. In quotes because
> I don't think the motive is at all dishonest but I suspect there is one -
> reading between the lines, there's been a few mentions about how the
> current Erlang is more difficult to parse/analyse because match patterns
> need extra information about which variables are already bound and to what.
> Am I inferring correctly that this EEP also serves a simplification of the
> language (from the POV of a machine), which is possibly related to some
> internal static analysis that WhatsApp is doing/would like to do, or
> perhaps is related to the fabled static typed Erlang that they are said to
> be working on? This may well be something that the community at large be
> interested in!
> 
> That's all from me. I hope we can all take a deep breath (or a few, for
> good measure) before sending our next messages to this thread and remember
> that we are all a part of the same, and _already_ small Erlang community,
> so I'd really like to see more posts in the vein of "let's see how we can
> settle our differences" than "not on _my_ lawn!".
> 
> All the best,
> Karl

-- 

/ Raimo Niskanen, Erlang/OTP, Ericsson AB