[Python-Dev] Re: A cute new way to get an infinite loop

[Terry Reedy]

"Tim Peters" <tim.peters at gmail.com> wrote in message 
news:1f7befae040923012645bc07f8 at mail.gmail.com...
>>>> x = [1]
>>>> x.extend(-y for y in x)

Very similar to this old way (2.2 and I presume before):
>>> l=[1]
>>> for i in l: l.append(i)
...
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
KeyboardInterrupt
>>> len(l)
1623613

but admittedly a bit more baroque ;-)

So, are things like this a programming bug, interpreter bug, or language 
definition bug?  or just a 'gotcha'?

Terry J. Reedy