Just a little addition if one wants to parse a space separated text file line by line.
read_file = function (path)
local file = io.open(path, "rb")
if not file then return nil end
local lines = {}
for line in io.lines(path) do
local words = {}
for word in line:gmatch("%w+") do
table.insert(words, word)
end
table.insert(lines, words)
end
file:close()
return lines;
end