Lazy evaluation of map

Question

I recently read that one benefit of map in Python 3 was that it is lazy. That means, it is better to do

map(lambda x: x**2, range(10**100))
         


        

Answer 1

There are many benefits; for example, it makes it easier to write memory efficient code.

def take_up_a_lot_of_memory(*args):
    """
    A contrived example of a function that uses a lot of memory
    """
    return sum([i ** 2 for i in range(10 ** 6)])

megasum = sum(map(take_up_a_lot_of_memory, range(1000)))

Also, sometimes you can terminate a calculation early without iterating through all of the map results, and so avoid redundancy.