Running the new Elixir formatter

There are two things: we don’t want projects to have many formatter related files. So between adding a .formatter.exs or .external_formatter.exs to source control, I would rather keep the first and have a single file.

And the second is that loading and parsing the Mixfile.project is going to add a bunch of indirection if all we want to load the formatter options. Especially because the formatter was designed to work without a project.

Yes but then you have things like the phoenix_ecto project which exists to manage the ecto dependencies for you in regards to phoenix. Maybe the best way to go here is to be opt-in?

mix format.import_deps ecto phoenix