Change numbering style to Bengali in nested ordered list

Question

I am writing a document which is mainly in Bengali but also contains English. I have been able to change the section and subsection numbers to Bengali using the method described here by Davislor. However, this doesn't change the numbering style to Bengali for nested lists.

As can be seen from the image, for the inner list of the nested list, as the numbering style, English alphabets are used. I want to replace those with the Bengali alphabets (ক, খ, গ, etc). How can this be done?

Here is a minimal working example.

% !TeX program = xelatex
\documentclass[12pt]{article}

\usepackage{babel}

\babelprovide[maparabic]{bengali}
\babelfont{rm}{Shonar Bangla}
\babelfont[english]{rm}{Times New Roman}

\begin{document}
    \section{প্রথম অধ্যায়}
    Foo bar
    \begin{enumerate}
        \item ফু
        \begin{enumerate}
            \item বার
            \item ফু
        \end{enumerate}
        \item বার
    \end{enumerate}
\end{document}

I am using MiKTeX and XeLaTeX.

Answer 1

Glad you found that helpful. Short answer: add the option alph=alphabetic to babelprovide. Longer answer (which enables compatibility with LuaLaTeX and adds a few bells and whistles):

% Recommended with LuaLaTeX in TeX Live 2020 or later,
% but also works with XeLaTeX.
\documentclass[12pt]{article}
\tracinglostchars=2 % Warn if the current font lacks a character.
\usepackage{iftex}

\ifluahbtex % Includes LuaLaTeX in TeX Live 2020.
  \usepackage[bidi=basic, layout=sectioning.counters]{babel}
  \usepackage{fontspec}
  %% Will auto-detect the language on LuaLaTeX:
  \defaultfontfeatures{ Renderer=HarfBuzz, Ligatures=TeX, Scale=MatchLowercase }
  \babelprovide[onchar=ids fonts]{english}
\else % Another Unicode engine, such as XeLaTeX.
  \usepackage[bidi=default, layout=sectioning.counters, english]{babel}
  \usepackage{fontspec}
  \defaultfontfeatures{ Ligatures=TeX, Scale=MatchLowercase }
\fi

\babelprovide[import,
              main,
              maparabic,
              alph=alphabetic
             ]{bengali}

\babelfont{rm}
          [Scale=1.0, Language=Default]{Shonar Bangla}
\babelfont[english]{rm}
          [Ligatures=Common]{Times New Roman}

\begin{document}
    \section{প্রথম অধ্যায়}
    Foo bar
    \begin{enumerate}
        \item ফু
        \begin{enumerate}
            \item বার
            \item ফু
        \end{enumerate}
        \item বার
    \end{enumerate}
\end{document}

On LuaLaTeX, this document will automatically detect when you type in English and change languages, so you will see English text in Times New Roman and get hyphenation patterns, ligatures and so on.

XeTeX will treat all text as the default language unless you explicitly change it, which you can do by adding the command \babeltags{english=english} and writing \textenglish{Foo bar}. Otherwise, your English text will appear as Shonar Bengla. This would be more noticeable if your Bengali font did not support the Latin alphabet or if you were switching between LTR and RTL.