Tuple generator, and function/class syntax

[quazirfan]

Question 1: I know that I can generate a list of some numbers using list comprehension. And the same syntax works with set. This is not a lazy operation so the following code might take a while to complete.

[ x for x in range(100000000)]
{ x for x in range(100000000)}

But when I try to generate a tuple of some numbers using comprehension, it uses generator, and therefore lazy operation. The following code returns immediately.

( x for x in range(100000000))

I know that I can use tuple(x for x in range(100000000)) to get the expected result, but I am wondering why () triggers generator, but not with with [] and {}.

Question 2: As I am learning python, I was under the assumption range() is a generator function. But upon reading the python documentation I realized it is a class, not a function.

So, when I see a code that appears like something() - there is no way for me to find out if I am looking at a class instantiation or a function call without looking at the definition of something - Am I correct?