[erlang-questions] Elixir community, please be more responsible; Erlang community, please demand it.

Joe Armstrong erlang@REDACTED
Sun Mar 24 17:26:36 CET 2019

On Sun, Mar 24, 2019 at 1:54 PM Fred Hebert <mononcqc@REDACTED> wrote:
> On 03/24, Joe Armstrong wrote:
> >I for one welcome all the things the Elixir folks are doing - but I
> >have noticed the following:
> >
> >- Elixir folks are re-using Erlang libraries
> >- Erlang folks are not (it seems to me) reusing Elixir libraries
> >
> >The "how to call Erlang from Elixir" documentation is great - the
> >opposite "how to call Elixir from Elixir" is not (or have I missed something)
> >
> >Things like nerves, scenic, Phoenix etc. look great to me - but seem to be used
> >almost exclusively by Elixir folks.
> >
> >Has anybody made, for example, a pure Erlang interface to scenic?
> >
> Well, there are some limitations there.
> - You can use mix to build your Erlang project and then use Elixir in
>   there
> - You can use rebar3 with the rebar_mix plugin (along with an Elixir
>   install) to build Elixir dependencies (see
>   https://github.com/tsloughter/rebar_mix)
> But in all cases, you will not necessarily be able to use Elixir code
> when it heavily relies on macros at the call-site rather than
> internally. So for example, a lot of usage of _plugs_ in Phoenix rely on
> macros running within the controller compilation step to read the
> declaration and inline them "somewhere??" with no obvious way to do it
> without the macros.
> That specific stuff that relies on macros in _your Elixir code_ cannot
> be ported to work with _your Erlang code_, because, well, we don't have
> the same macro mechanisms available. Similarly, Erlang parse transforms
> may not remain fully applicable to Elixir modules in the future.
> This means that Ecto, which is a huge part of a lot of web framework
> usage, also won't be usable for Erlang users, since it is very
> macro-dependent.

Interesting - I'd imagined that after compilation you'd just end up
with beam code files after which you could call them from Erlang ...

Could this be rectified by a "better" macro processor for erlang - more
in the style of the Elixir macro processor ???

> But if you look at other libraries (or frameworks) such as Raxx
> (https://github.com/CrowdHailer/raxx), then this is a framework that is
> fully written in Elixir, yet usable from Erlang (there's a demo at
> https://github.com/CrowdHailer/greetings-ace-raxx-erlang-example).
> Similarly, a library such as https://github.com/ericmj/decimal for
> arbitrary precision arithmetic should be fine to use.
> This stuff has been available to rebar3 users since around late 2018, so
> I assume it has seen slow adoption due to its being rather new, but we
> (rebar3 maintainers) are confident that this bigger interplay is worth
> it and should be seeing adoption over time.
> Finally, the stuff we're setting up with the Erlang Ecosystem Foundation
> is also aimed at making language interplay easier for all languages of
> the ecosystem.

This would be great


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