New submission from Dominik V. <dominik.vilsmeier1...@gmail.com>:
[PEP 586](https://www.python.org/dev/peps/pep-0586/#shortening-unions-of-literals) specifies that Literal[v1, v2, v3] is equivalent to Union[Literal[v1], Literal[v2], Literal[v3]] Since the equality of Unions doesn't take into account the order of arguments, Literals parametrized with multiple arguments should not be order dependent either. However they seem to: >>> Literal[1, 2] == Literal[2, 1] False Compare with the equivalent form: >>> Union[Literal[1], Literal[2]] == Union[Literal[2], Literal[1]] True In addition to that, the PEP specifies that nested Literals should be equivalent to the flattened version (https://www.python.org/dev/peps/pep-0586/#legal-parameters-for-literal-at-type-check-time). This section is titled "Legal parameters for Literal at type check time" but since the PEP doesn't specify runtime behavior differently, I think it makes sense to assume it is the same. It seems to be different though: >>> Literal[Literal[1, 2], 3] typing.Literal[typing.Literal[1, 2], 3] >>> Literal[Literal[1, 2], 3] == Literal[1, 2, 3] False Also the flattening follows from the above definition `Literal[v1, v2, v3] == Union[Literal[v1], Literal[v2], Literal[v3]]` and the fact that Unions are flattened. ---------- messages: 380888 nosy: Dominik V. priority: normal severity: normal status: open title: Equality of typing.Literal depends on the order of arguments type: behavior versions: Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue42345> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
