Python Practice 7/9

Generators

A normal function returns once and hands back one value. A generator function uses yield instead of return, and can hand back many values, one at a time, pausing exactly where it left off between each one. Calling it doesn't run the body at all yet - it returns a generator object, and the code only runs as each value is pulled out.

That laziness is the whole point: list(squares(1000000)) on a normal function builds a million-item list in memory before you get anything back; a generator hands you the first value immediately and computes the rest only if you keep asking. list(some_generator()) or a for loop will pull every value out and collect them, same as any other iterable.

Your task: write a generator function squares(n) that yields the square of each integer from 1 to n, in order, one at a time, using yield instead of building and returning a list.

You'll practice:

Writing a generator function with yield
Understanding that calling it returns a lazy generator, not a list

# Write squares(n): a generator that yields 1*1, 2*2, ..., n*n, one at a time.
def squares(n):
    pass