There is something I do not understand in the passing of parameters from TeX to LuaTex.
This is my TeX definition:
\def\ListSort[#1]#2{\directlua{hvdm.listsort([===[#2]===],[===[#1]===])}}

Calling \ListSort[sep={ + }]{} delivers the string  'sep={ + }' into LuaTeX as the printout in the logfile shows and as intended.
However in \ListSort[{ + }]{} the braces have disappeared and transferred is nothing more than ' + '.

Why is the transfer messing up the character string I am passing by removing the outer braces? Is this a bug or is it an unavoidable consequence of the TeX-LuaTeX interface?

dr. Hans van der Meer