Joining a set of ordered-integer yielding Python iterators

Question

Here is a seemingly simple problem: given a list of iterators that yield sequences of integers in ascending order, write a concise generator that yields only the integers th

Answer 1

def postings(posts):
    sets = (set(l) for l in posts)
    return sorted(reduce(set.intersection, sets))

... you could try and take advantage of the fact that the lists are ordered, but since reduce, generator expressions and set are all implemented in C, you'll probably have a hard time doing better than the above with logic implemented in python.