I am attempting to use MyPy with modules that use ruamel.yaml and Mypy cannot find ruamel.yaml even though Python has no problem finding it. I am puzzled because I can't find a module called YAML.py or class called YAML either, even though these statements work in Python:
from ruamel.yaml import YAML
yaml = YAML()
x = yaml.load()
What do I need to do to get MyPy to recognize ruamel.yaml?
A workaround is to run without the incremental logic of mypy:
python -m mypy --no-incremental myfile.py
Background
There is a known issue in mypy, see here.
In summary:
Something is not working with the incremental logic of mypy when it is encountering ruamel.
When you run it once, all goes ok. This is the command:
python -m mypy myfile.py
Then, when you run it again, you get an error:
error: Skipping analyzing 'ruamel': found module but no type hints or library stubs [import]
Then, when you run it again, it all goes ok
etc.
You should not be looking for a file YAML.py. The YAML in
yaml = YAML()
is a class that is defined in ruamel/yaml/main.py and that gets imported into ruamel/yaml/__init__.py (both under site-packages). That is why you do:
from ruamel.yaml import YAML
(the alternative would be that there is a file yaml.py under the directory ruamel, but the loader/dumper is a bit too much to put in one file).
What might work if the above knowledge doesn't help you resolve things, is explicitly set the global flag mypy_path or the environment variable MYPYPATH. This has to include the directory in which the directory ruamel is located.
( I could not find it mentioned in the documentation, but from the source ( mypy/build.py:mypy_path() ) you can see that this is supposed to be a string that gets split on os.pathsep (which is the colon (:) on my Linux based system))
I have the same issue.
Even after setting MYPYPATH=./.venv/lib/python3.7/site-packages
A temporary 'solution' is ignoring the missing import exception
mypy --ignore-missing-imports