Why not go all the way? Have that in your aliases section of mix.exs:

      check: [
        "compile --warnings-as-errors",
        "format --check-formatted",
        "credo --strict",
        "coveralls.html",
        "dialyzer --format short"
      ]

Then just run mix check and voila, you almost have locally running CI.

For my Elixir, Rust, JavaScript, JSON and OCaml editing I use formatters even if I don’t like all of their decisions how things should look like.

Truth is, our code will be read by other people so I prefer to be a good citizen.

I love using the formatter, and specifically format on save in my editor, because it allows me to see if my code is right as it happens. If I save my file and everything snaps into place, I know I did things right. If it doesn’t, I know that I have a syntax error somewhere in the code I just wrote. Saves me from flicking back and forth to the server and my editor.

I love tabular code.

This

  defp decode(addr_t(:ind), _dest, data) do
    case data do
      <<0::6, data::bits>>            -> {:t_data_ind, nil, data}
      <<0b01::2, seq::4, data::bits>> -> {:t_data_con, seq, data}
      <<0b1000_0000::8>>              -> {:t_connect, nil, <<>>}
      <<0b1000_0001::8>>              -> {:t_discon, nil, <<>>}
      <<0b11::2, seq::4, 0b10::2>>    -> {:t_ack, seq, <<>>}
      <<0b11::2, seq::4, 0b11::2>>    -> {:t_nak, seq, <<>>}
      _                               -> {:error, :invalid_tpci}
    end
  end

for me, is just way more readable than

  defp decode(addr_t(:ind), _dest, data) do
    case data do
      <<0::6, data::bits>> -> {:t_data_ind, nil, data}
      <<0b01::2, seq::4, data::bits>> -> {:t_data_con, seq, data}
      <<0b1000_0000::8>> -> {:t_connect, nil, <<>>}
      <<0b1000_0001::8>> -> {:t_discon, nil, <<>>}
      <<0b11::2, seq::4, 0b10::2>> -> {:t_ack, seq, <<>>}
      <<0b11::2, seq::4, 0b11::2>> -> {:t_nak, seq, <<>>}
      _ -> {:error, :invalid_tpci}
    end
  end

but I know, that most people don’t like it, so it will never be possible to format Elixir-code like that. And that is a good thing. It’s important to have a common code style everyone can read. So I keep formatting my C files in crazy ways, because in C, everybody complains about your style anyway and there will never be any agreement.

I still use the formatter even though I really really hate some of the things it does (like no trailing comma’s on multi-line things) just for consistency with what everyone else expects. I do the same with rust’s formatter and C++ formatting via clang and others as well. I may do some slight tweaks in configs (hard tabs instead of spaces because screw 3+width indentations when I’m in a terminal) when possible, but otherwise try to keep it as ‘vanilla’ as I can. It makes it easier for other people to look at and PR to your code.