[luatex] macros to invoke lua in LaTeX

[Karl Berry]

      If I remember correctly, the original idea was to add "pdf" in front
    of all the primitives that were particular to pdfTeX, and it thus meant
    "pdfTeX" and not "PDF", at least originally (am I right?)  But it is
    indeed not the most intuitive naming convention.

Maybe not intuitive in all cases, but very very useful for preventing
clashes.  The LuaTeX practice of choosing names for primitives that are
meaningful, but without any such prefix, seems quite problematic to me.
Not just right now, but at any time in the future: if a new primitive
\foo is introduced, any existing package that happens to use \foo is
potentially affected.  Sure, it can be worked around, but it introduces
unnecessary instability and incompatibility, it seems to me.

Sorry to be such a drag.