local data = {}

local getinfo = debug.getinfo;

local function linehook(ev, li)

	local S = getinfo(2, "S");

	if S and S.source and S.source:match"^@" then

		local file = S.source:sub(2);

		local lines = data[file];

		if not lines then

			lines = {};

			data[file] = lines;

			for line in io.lines(file) do

				lines[#lines+1] = line;

			end

		end

		io.stderr:write(ev, " ", file, " ", li, " ", lines[li], "\n");

	end

end

debug.sethook(linehook, "l");