Python generators

We can write generators in Python like the following:

def infinite_sequence():
    x = 0
    while True:
        yield x
        x += 1

The result generator object can be repeatedly invoked with .next() to get the next value:

seq = infinite_sequence()
next(seq) # 0
next(seq) # 1
next(seq) # 2

Python generator are iterables, so we can do something like this:

for i in infinite_sequence():
    print(i)
    # Note that this loop will not terminate since the generator above is infinite

Generator Expressions

Python has a shorthand syntax for producing generators. The syntax is very similar to list comprehension, though it uses paranthesis:

generator = (x ** 2 for x in range(10)) 

The generator expression doesn’t seems to be able to express “infinite” generators.