Hello Elixir friends,

I want to make one of my Elixir available/usable for our Erlang friends and be a “good BEAM citizen”. I was also told, that there isn’t really a good benchmarking library for Erlang so it seemed like a great idea.

Problem: I can’t figure out how to install Elixir libraries in Erlang. Threads like Writing a library for use in both Elixir and Erlang as well as the prominent Erlang/rebar3 usage on hex.pm made me think this was possible (although I always sort of wondered where it gets all the Elixir from)…

I setup a little test respository. However, benchee can not be found and neither can any other popular elixir hex package I can think of:

tobi@speedy ~/github/benchee_erlang $ rebar3 update
===> Updating package registry...
===> Writing registry to /home/tobi/.cache/rebar3/hex/default/registry
===> Generating package index...
===> Writing index to /home/tobi/.cache/rebar3/hex/default/packages.idx
tobi@speedy ~/github/benchee_erlang $ rebar3 compile
===> Package <<"benchee">> not found. Fetching registry updates and trying again...
===> Updating package registry...
===> Writing registry to /home/tobi/.cache/rebar3/hex/default/registry
===> Generating package index...
===> Writing index to /home/tobi/.cache/rebar3/hex/default/packages.idx
===> Package not found in registry: <<"benchee">>.
tobi@speedy ~/github/benchee_erlang $ rebar3 pkgs | grep poison
tobi@speedy ~/github/benchee_erlang $ rebar3 pkgs | grep phoenix

(btw. yes I have the rebar3_hex plugin installed but I think it does something else)

Adding benchee as a git dependency I get this error:

tobi@speedy ~/github/benchee_erlang $ rebar3 compile
===> Verifying dependencies...
===> Fetching benchee ({git,"git://github.com/PragTob/benchee.git"})
===> WARNING: It is recommended to use {branch, Name}, {tag, Tag} or {ref, Ref}, otherwise updating the dep may not work as expected.
===> Dependency failure: Application benchee not found at the top level of directory /home/tobi/github/benchee_erlang/_build/default/lib/benchee

It’s from this rebar3 issue - basically I don’t follow the standard rebar3/erlang project structure and yeah I’m an elixir project, so sure it doesn’t work.

So what do I do? Elixir and Erlang/rebar3 both use hex.pm and elixir people can use Erlang stuff but not the other way around? Do I just not know how?

How can I allow an Erlang project to use an Elixir library? Do they have to copy the files and compile them themselves to beam files? Do I setup a separate rebar3 package?

Sorry my erlang knowledge is also rather… improvable

I feel like (and hope) I’m really missing something so please feel free to point it out. Thank you in advance