I don't know what this is supposed to prove, it just shows that the generator is lazy while the list isn't. It seems unrelated to scoping issues or leaking variables.
If you instead fully evaluate the generator expression before calling any of the functions (for example, by passing it to the list constructor), you get the same behavior as the list comprehension case:
>>> [f() for f in list(lambda: i for i in range(0, 10))]
[9, 9, 9, 9, 9, 9, 9, 9, 9, 9]Side note: I think that commenters above didn't quite understand what I meant by "leaking", because there's more than one scope boundary here. Roughly speaking, any comprehension or loop can be desugared into something that looks like a C-style for-loop:
/* scope 1 */
for (/* scope 2 */) {
/* scope 3 */
}