Today I Learned

A Hashrocket project

Compile an Elixir dependency as you change it

In an Elixir project, the dependencies are one-time compiles. That makes sense when you know the dependency is not going to change. It stops making sense, however, when you need to explore how a dependency works by adding debug statements like IO.puts. Or when you find something in a dependency you want to change and need to test that change in an application.

In those cases Elixir provides the facility to compile a dependency each time it has a change in one of the component files just like how compilation in your mix app works. You can enable this by providing a path to the location of the dependency in the mix.exs file:

defp dep do
  [
  ...
  {:wallaby, '~> 0.16.1', path: 'deps/wallaby'}
  ...
  ]
end

In this case the path is set to the local deps dir, where the dependency already exists, but you can also set it to a working directory for that library.

Looking for help? Elixir is quickly gaining momentum for web applications that need concurrency, performance, and the ability to connect to many different clients. The developers at Hashrocket are learning along with the rest of the development community that Elixir and Phoenix are viable Rails alternatives for the right application. Contact us if you need help with your Elixir project.