Problem is, we already have a syntax for empty lists [], empty tuples (), and {} is taken for an empty dict. So having a syntax for an empty set actually makes sense to me
Python needed a breaking change for Unicode and a breaking change for exceptions and took it ages ago for a better future today - and it's still remembered as a huge PITA by everyone. I think you'll find everyone in the Python community disagreeing with you about a not-backwards-compatible Python 4.
If Python actually incremented the major version every time they broke backwards compatibility, we'd be on something like Python 36 by now.
Almost every version they break existing code. This is why it's common for apps written in Python to depend on specific Python versions instead of just "anything above 3.x".
Every minor release of Python is a breaking change. They deprecate stuff all the time, and remember the stdlib and the wider ecosystem has to also move in concert so the breaking changes cascade.
By major version I meant minor version, 3.13 -> 3.14 is a minor version in Python, but a major source of breaking changes, that is what I meant. There will be no Python 4
Are you suggesting to bump to Python 4 in order to be able to write `{}` instead of `set()` (or `{/}`) and simultaneously break all existing code using `{}` for dicts?
Breaking {} to be an empty set would be a HUGE breaking change, a _lot_ of code is already written where it is expected to be an empty dict. I don't think anyone in the Python committee would agree with breaking that
Making sense, and being good, is not necessary the same.
Yes, having a solution for this makes sense, but the proposed solutions are just not good. Sometimes one has to admit that not everything can be solved gracefully and just stop, hunting the whale.
For reasons I don't think I understand, using the functions is "discouraged" because "someone might muck with how those functions work" and the python world, in it's perfect wisdom responded "Oh of course" instead of "That's so damn stupid, don't do that because it would be surprising to people who expect built in functions to do built in logic"
Yes but they are not equivalent. dict and list are factories; {} and [] are reified when the code is touched and then never reinitialised again. This catches out beginners and LLMs alike:
They are equivalent. In function signatures (what your article is talking about), using dict() instead of {} will have the same effect. The only difference is that {} is a literal of an empty dict, and dict is a name bound to the builtin dict class. So you can reassign dict, but not {}, and if you use dict() instead of {}, then you have a name lookup before a call, so {} is a little more efficient.
I wrote the link and yes it does. Module evaluations reify {}, [], etc. once. That is why people keep making subtle bugs when they do `def foo(a=[]):` unaware that this will in fact not give you a brand new list on every function call.
Factory functions like list/tuple/set are function calls and are executed and avoid this problem. Hence why professional python devs default to `None` and check for that and _then_ initialise the list internally in the function body.
Adding {/} as empty set is great, sure; but that again is just another reified instance and the opposite of set() the function.
There is no difference between “def f(x={})” and “def f(x=dict())”, unless you have shadowed the dict builtin. They both have exactly the same subtle bug if you are mutating or return x later.
