A few things that annoy me with the opinionated formatter (when the line_length is exceeded) are

<<0,1,2,3,..>> Binary gets expanded to

<<
0,
1,
2,
3,
..
>>

Extra indent

values = [{0, "a"}, {1, "c"}, {2, "e"}]


value = values 
|> Enum.find_value(fn{key, letter}-> key == 1 && letter end)
|> String.upcase()
|> Base.encode64()

# Formatted

value = 
  values
  |> Enum.find_value(fn {key, letter} -> key == 1 && letter end)
  |> String.upcase()
  |> Base.encode64()

I feel without the extra indent its clearer to read if the function has more scopes.

and / or get placed at end of line

    Enum.filter(values, fn{k,v}->
      k == 5
      and k != 7
      and v != "a"
    end)


    Enum.filter(values, fn {k, v} ->
      k == 5 and
        k != 7 and
        v != "a"
    end)

Reading from left to right makes it take longer to comprehend. If you read right to left its natural tho.

If line gets expanded in a cond

  Enum.filter(values, fn {k, v} ->
      cond do
        k == 5 and k == 5 and k == 5 and k == 5 and k == 5 and k == 5 and k == 5 and k == 5 -> false
        k != 7 -> false
        v != "a" -> false
        true -> true
      end
    end)

    Enum.filter(values, fn {k, v} ->
      cond do
        k == 5 and k == 5 and k == 5 and k == 5 and k == 5 and k == 5 and k == 5 and k == 5 ->
          false

        k != 7 ->
          false

        v != "a" ->
          false

        true ->
          true
      end
    end)

Extra spaces even tho the lines are short, the results are placed on seperate lines.

Does anyone have any idea how to slightly tune the formatter? I know its meant to be opinionated and the official answer will be, if you dont like it dont use it.