I wanted to use the zeromq chumak library in Elixir. Since, chumak is an Erlang implementation, one should be able to use it without any modifications. I wasn't able to get it working. So decided to make changes to the mix dependency source code of chumak to find out what was going on. I realized the compiling the application did not compile the changes in chumak source code I made. Thanks to this post by hashrocket I learnt that to be able to compile the source code of the dependecy we should add it to the dependencies as follows.

defp deps do
  [
    ...
    {:chumak, '~> 1.4.0', path: 'deps/chumak'}
    ...
  ]
end

Additionally,

1. I noticed that you cannot simply use the recompile command in iex shell to compile the dependency changes.

2. You have to exit the current iex shell and start a new one with iex -S mix.