It is useful to have the interpreter derive the type of a variable automatically. This on its own is similar to the
auto keyword in C++11. However, in Python variables can change their type after being declared for the first time. This potentially can cause a lot of errors. I haven't seen any reasonable use case for this, besides changing from or to
For performance reasons, PyPy claims to be written in what they call RPython, which goes into this direction. However, it seems like there is neither a standard for this nor a way to make the interpreter complain about type changing.
Is there a way to prevent variables from changing their type in Python?