Can I use an easy programming language with XeTeX?

My PythonTeX package is another Python-based option. PythonTeX was primarily developed for mathematical and scientific applications, but it's also suitable for much general-purpose work. I've included a few basic examples of creating macros with PythonTeX below. You do have to be careful about catcodes if you are working with special characters.

\documentclass{article} 
\usepackage{pythontex}

\begin{document}

Basic math:  \py{5324/251}

Macros that more closely interact with TeX:

\newcommand{\reverse}[1]{\py{"#1"[::-1]}}

\reverse{A sentence!}

\newcommand{\listtotabular}[1]{
    \begin{tabular}{|c|c|c|c|}
    \hline
    \py{'&'.join("#1".split(','))} \\
    \hline
    \end{tabular}
}

\listtotabular{First, Second, Third, Fourth}

\end{document}

In addition to the examples above, and the examples included with the documentation, you might also look at the following examples.

• Plotting the derivative of a function
• Using Python to create tikz
• Solving an equation

• Python: package python, example
• Perl: PerlTeX, documentation
• (LuaTeX: reference, documentation for LuaLaTeX) (not for XeTeX)

While I haven't tried, you might be able to use bashful to interact with programs written in other languages via stdin and stdout.

I had no problems with a simple example as long as I compiled with -shell-escape:

\documentclass{article}
\usepackage{bashful}
\def\fortune{\splice{fortune}}
\begin{document}
\fortune

\fortune
\end{document}

I am not sure about the polyglossia issue that is mentioned in the documentation.