[luatex] TeXLua as one's Lua interpreter

[Dirk Laurie]

I'm writing a large Lua program that will mainly be of interest to
people that probably have TeX installed but not necessarily Lua.
Lua knowledge is not a prerequisite end it would be adequate
to run the program using `texlua`. However, it should also run
under Lua 5.3. It's easy to check which is actually running.

I need UTF-8 support without asking the user to install
any support libraries. That means one of:
1. Simulate Lua 5.3's utf8 support in texlua.
2. Provide (maybe only a subset of) texlua's unicode.utf8 and
extra string library functions in Lua 5.3.
3. Design a unified interface, doing some adaptation at both ends.

Is anything of the kind already in existence?