Few people would be able to guess what it means the first time they see it, or think of it as the "obvious way" to merge two dicts
[...]
{d1, d2} ignores the types of the mappings and always returns a dict. type(d1)({d1, d2}) fails for dict subclasses such as defaultdict that have an incompatible __init__ method.
Though I'm not personally convinced that + would be more obvious or that dict subtypes are merged often enough for this to matter.
Few people would be able to guess what it means the first time they see it, or think of it as the "obvious way" to merge two dicts
[...]
{d1, d2} ignores the types of the mappings and always returns a dict. type(d1)({d1, d2}) fails for dict subclasses such as defaultdict that have an incompatible __init__ method.
Though I'm not personally convinced that + would be more obvious or that dict subtypes are merged often enough for this to matter.
[1] https://www.python.org/dev/peps/pep-0584/#d1-d2