Hello everybody, Scala 3 propose the a new syntax for Union type. See here <https://dotty.epfl.ch/docs/reference/new-types/union-types.html>. I propose to add a similar syntax in Python. # Operator for Union assert( int | str == Union[int,str]) assert( int | str | float == Union[int,str,float]) # Operator for Optional assert( ~int == Optional[int]) Now, it's possible to write: def fn(bag:List[int | str], option: ~int = None) -> float | str: ... in place of def fn(bag:List[Option[int,str]], option: Optional[int] = None) -> Union[float,str]: ... I think these syntaxes are more clear, and can help with the adoption of typing. I test and implement these ideas in a two fork : One for CPython <https://github.com/pprados/cpython> and one for MyPy <https://github.com/pprados/mypy>. See the branches add_OR_to_types (for Union syntax) or add_INVERT_to_types (for Union and Optional syntax). How I implement that ? I add the operators __or__ and __revert__ to PyType_Type. The C code is similar of : from typing import * def type_or(self,right): return Union[self,right] type(type).__or__ = type_or Actually, the accepted syntax for typing is : annotation: name_type name_type: NAME (args)? args: '[' paramslist ']' paramslist: annotation (',' annotation)* [','] I propose to extend the syntax to : annotation: ( name_type | or_type | invert_type ) name_type: NAME (args)? args: '[' paramslist ']' paramslist: annotation (',' annotation)* [','] or_type: name_type '|' annotation invert_type: '~' annotation What do you think about that ? The draft of a PEP is here <https://github.com/pprados/peps/blob/master/pep-9999.rst>. Regards