This example was poorly written. So I decided to rewrite it here publicly at github.

lxp.lua

#!/usr/bin/env lua

-- Lib Expat example with cURL

local cURL = require "cURL"
local lxp = require "lxp"

tags = {}
items = {}
callback = {}

function callback.StartElement(parser, tagname)
    tags[#tags + 1] = tagname
    if (tagname == "item") then
        items[#items + 1] = {}
    end
end

function callback.CharacterData(parser, str)
    if (tags[#tags -1] == "item") then
        --we are parsing a item, get rid of trailing whitespace
        items[#items][tags[#tags]] = string.gsub(str, "%s*$", "")
    end
end

function callback.EndElement(parser, tagname)
    --assuming well formed xml
    tags[#tags] = nil
end

new_callback = lxp.new(callback)

-- create and setup easy handle
handle_curl = cURL.easy_init()
handle_curl:setopt_url("https://www.archlinux-br.org/feeds/news/")

multi = cURL.multi_init()
multi:add_handle(handle_curl)

for data, type in multi:perform() do
    -- ign "header"
    if (type == "data") then
        assert(new_callback:parse(data))
    end
end

--finish document
assert(new_callback:parse())
new_callback:close()

for i, item in ipairs(items) do
   for keys, values in pairs(item) do
      print(keys, values)
   end
   print()
end