Serhiy Storchaka <storchaka+cpyt...@gmail.com> added the comment:
It is a difference with typing.Union which can cause confusion. If the union
type is like a tuple and we leave a 1-type union, why do we bother with
deduplication? Why int | str | int is collapsed into int | str?
Also it complicates the comparison implementation and produces surprising
exceptions:
>>> int | str == {}
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'dict'
Also it breaks one of fundamental properties -- equal objects should have equal
hashes.
>>> (int | int) == int
True
>>> hash(int | int) == hash(int)
False
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue44636>
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