How to implement an efficient infinite generator of prime numbers in Python?

Question

This is not a homework, I am just curious.

INFINITE is the key word here.

I wish to use it as for p in primes(). I believe that this is a built-

Answer 1

Here's a generator that's a little truer to how it's done in Haskell: filtering against composites of known primes, then adding the remaining primes to the list.

def gen_primes():
    primes = []
    i = 2
    while True:
        prime = True
        for p in primes:
            if not (i % p):
                prime = False
                break
        if prime:
            yield i
            primes.append(i)
        i += 1