What's happening here?

Question

uncommenting the only commented line fails the code. why is it?

also, without uncommenting, if i try list comprehension instead of generator, there is RecursionError.

https://code.sololearn.com/cRvoK31O3qFN/?ref=app

Answer 1

In the first part there is a generator. And a generator is just a set of commands yet to be executed.

A = (i for i in range(67))

Here, A is a generator. It only knows 'what to do' and hasn't done anything yet. It hasn't created the sequence of numbers.

That is why this also runs without error:

def evens(): #infinite sequence
n = 0
while True:
yield i
i += 2

B = evens()

Now when you execute the generator, you may get error since it is only now that the generator-code is running.

For example,

print(list(B)) #memoryerror

here, the actual sequence is being created hence error.

Another example:

def recur():
yield 1 #to make it a generator
yield from recur()

C = recur() #no error
print(list(C)) #recursionerror

Answer 2

Harsha S
If n=50, then your code works on Sololearn, so I think fibonacci 500 may be too big for the allowed processing time on Sololearn.

It fails above n = 498