Lazy map function in Python

Question

Is there a way of making map lazy? Or is there another implementation of it built-in in Python?

I want something like this to work:

from itertools import count

for x in map(lambda x: x**2, count()):
    print x

Of course, the above code won't end, but I'd like just to enter any condition (or more complex logic) inside the for and stop at some point.

Answer 1

use itertools.imap on Python 2.x or upgrade to Python 3.x

You can also just use a simple generator expression that is far more pythonic:

foo = (x**2 for x in count())

Answer 2

itetools.imap is lazy.

In [3]: itertools.imap?
Type:       type
String Form:<type 'itertools.imap'>
Docstring:
imap(func, *iterables) --> imap object

Make an iterator that computes the function using arguments from
each of the iterables.  Like map() except that it returns
an iterator instead of a list and that it stops when the shortest
iterable is exhausted instead of filling in None for shorter
iterables.