Elixir script file without extension is ignored by `mix format`

My env and context

• Elixir 1.19.1
• Erlang 28.1.1
• Editor: vscodium (Basically same as vscode)
• Vscodium Extension: ElixirLS v0.30.0
• Not sure if it matters: zsh, macos arm
• I’m a beginner in elixir and beam

My problem

I have a language agnostic repo, and I’m trying to get my editor to format my script files.

Example scripts/upcase

  #!/usr/bin/env elixir

  case System.argv() do
    [] -> IO.read(:stdio, :all)
    args -> Enum.join(args, " ")
  end
  |> String.upcase()
  |> IO.puts()

When I open this file on my editor, it detects the language and syntax highlights correctly but format file command doesn’t work.

So I thought I could do it via mix format but that didn’t work either, silently exits without formatting.

What I tried

1. mix format scripts/upcase is silently exiting, no changes.
2. Could it be because my lang agnostic repo doesn’t have .formatter.exs file?
   1. mix format –-dot-formatter ~/.formatter.exs scripts/upcase

   2. ❯ cat ~/.formatter.exs                                        
      [
        inputs: ["scripts/upcase"]
      ]
      

   3. still silently exiting, file is not changed.
3. After reading the mix format docs carefully, I realized I can pipe string into mix format -

   1.   mix format - < scripts/upcase > /tmp/temp && mv /tmp/temp scripts/upcase
      

   2. Yes this works, but it’s very clunky.

Why could this be?

So I dived into the source, and I think this block is the culprit

defp find_formatter_for_file(file, formatter_opts) do
  # ...
  cond do
    # ...
    ext in ~w(.ex .exs) ->
        &elixir_format(&1, [file: file] ++ formatter_opts)
    true ->
        & &1
  end
  # ...
end

Can I create a formatter plugin for extensionless files?

I thought this could be a solution, but I am not sure what’s the best way to do this since elixir_format/2 is a private method, see on github.

Should I copy the method’s body, and use Code.format_string!/2 ?