Behavior of statistics.mean

[cametan]

Oops! It seems like Python's Bug.

Let's show the code again.

# unfoldr: the co-recursive iterator
class unfoldr:
    def __init__(self, f, seed):
        self.f = f
        self.seed = seed
    def __iter__(self):
        return self
    def __next__(self):
        match self.f(self.seed):
            case a, b:
                self.seed = b
                return a
            case None:
                raise StopIteration

Now, let's see the code showing the weird behavior again.

# Q: You input numbers. If you input 0, it means stopping input. Write a program showing the average you have inputted.
def buzz():
    from statistics import mean
    def foo(x):
        i = int(input())
        return None if i == 0 else (i, x + 1)
    print(mean(unfoldr(foo, 0)))

My Xubuntu has Python 3.10, 3.11, 3.12. I would show the comparison.

# On Python 3.12.1
>>> buzz()
1
2
3
4
5
6
7
8
9
10
0 # the first 0
0 # the second 0 -> that makes buzz finished and return the result
5.5

# On Python 3.11.7 
>>> buzz()
1
2
3
4
5
6
7
8
9
10
0 # the first 0
0 # the second 0 -> that makes buzz finished and return the result
5.5

# On Python 3.10.12
buzz()
1
2
3
4
5
6
7
8
9
10
0 # This stops input as I expected
5.5

This means, since Python 3.11, some "change" in Python causes its strange behavior.