Hi, using gettext, I’m trying to define a locale variant to handle formal vs informal french (so “fr” vs “fr@formal” in my case).

I tried to add a plural module to my app, as specified in the docs, but it seems to completely ignore it.

defmodule MyApp.Plural do
  @behaviour Gettext.Plural

  # Fallback to Gettext.Plural
  def nplurals("fr@formal"), do: 2
  def nplurals(locale), do: Gettext.Plural.nplurals(locale)

  def plural("fr@formal", 0), do: 0
  def plural("fr@formal", 1), do: 1

  def plural(locale, n) do
    Gettext.Plural.plural(locale, n)
  end
end

defmodule MyApp.Gettext do
  use Gettext, otp_app: :my_app, plural_forms: MyApp.Plural
end

Running mix gettext.merge priv/gettext --locale fr@formal gives me

** (Gettext.Plural.UnknownLocaleError) unknown locale “fr@formal”. If this is a locale you need to handle,
consider using a custom pluralizer module instead of the default
Gettext.Plural. You can read more about this on the Gettext docs at
Gettext.Plural — gettext v1.0.2

What am I missing?