This is a handy recursive data printer.

rPrint example.txt

> rPrint({first={true,1.3,"abc",{1,2,5}},22,33,last={nil,5},2},nil,"Junk", ngx.say)
Junk	table
Junk	[1]	number	22
Junk	[2]	number	33
Junk	[3]	number	2
Junk	[last]	table
Junk	[last]	[2]	number	5
Junk	[first]	table
Junk	[first]	[1]	boolean	true
Junk	[first]	[2]	number	1.3
Junk	[first]	[3]	string	abc
Junk	[first]	[4]	table
Junk	[first]	[4]	[1]	number	1
Junk	[first]	[4]	[2]	number	2
Junk	[first]	[4]	[3]	number	5

rPrint.lua

--[[ rPrint(struct, [limit], [indent])   Recursively print arbitrary data. 
	Set limit (default 100) to stanch infinite loops.
	Indents tables as [KEY] VALUE, nested tables as [KEY] [KEY]...[KEY] VALUE
	Set indent ("") to prefix each line:    Mytable [KEY] [KEY]...[KEY] VALUE
--]]
function rPrint(s, l, i, pFunc) -- recursive Print (structure, limit, indent, printFunction)
	l = (l) or 100; i = i or "";	-- default item limit, indent string
	pFunc = pFunc or print          -- default print function
	if (l<1) then pFunc "ERROR: Item limit reached."; return l-1 end;
	local ts = type(s);
	if (ts ~= "table") then pFunc (i.."\t"..ts.."\t".., s); return l-1 end
	pFunc (i.."\t"..ts);           -- print "table"
	for k,v in pairs(s) do  -- print "[KEY] VALUE"
		l = rPrint(v, l, i.."\t["..tostring(k).."]", pFunc);
		if (l < 0) then break end
	end
	return l
end	

An user-defined print method has been added into rPrint.