Why is bool([()])==True but bool(([]))==False ?

Question

My question is based on a challenge. Does anybody have an explanation for this behaviour?

Answer 1

Because 1st bool means list object with tuple value in it i.e [ () ] . Although tuple is empty, it doesn't matter because bool check whether list [] contain something. This leads to True.
2nd bool is false because (( [] )) evaluate to simply [] cuz in case of (( something )) , parenthesis are simply code block. Hope it helps :)

Answer 2

@Sylar & Davy:
Thank you both for your explanations! :-)

I have just found out that it is possible to get True in both cases, if you write the 2nd case like:

print(bool(([],)))

Mind the comma!
Then it is not just a pair of brackets but a tuple.
It is the same problem with (3) and (3,).

Answer 3

The first one is a list containing an ( empty) element, making the list not empty, the second one is an empty list.

Answer 4

Thanks. I was just wondering how that would work!