[wruza]

OpenResty, for one, allows that via grouping queries, rather than results:

    local requests = { "/mysql", "/postgres", "/redis", "/memcached" }
    local responses = { ngx.location.capture_multi(requests) }

    for i, response in ipairs(responses) do
        print(response.foobar)
    end

But instead ngx could lazy-evaluate responses with help of metatables (see my other comment).