[Feature Request] Implement `__iter__` on PythonObject

[xcloudplatform]

Review Mojo's priorities

• [X] I have read the roadmap and priorities and I believe this request falls within the priorities.

What is your request?

when using python list it should not be of opaque type PythonObject. instead, it should be transparently bridged into list like object

What is your motivation for this change?

%%python
package_list = [
    "nltk",
    "gensim",
    "fasttext",
    "spacy",
    "textblob",
    "pytorch_lightning",
    "fastai",
    "keras_tuner",
    "hyperopt",
    "pycaret",
    "shap",
    "eli5",
    "catboost",
    "xgboost",
    "lightgbm",
    "prophet",
    "opencv-python",
    "dlib",
    "imbalanced-learn",
    "tpot"
]




from PythonInterface import Python


available_packages = []
for package_name in package_list:
    try:
        Python.import_module(package_name)
        available_packages.append(package_name)
    except:
        pass
available_packages



error: Expression [14]:18:25: 'PythonObject' does not implement the '__iter__' method
    for package_name in package_list:

Any other details?

x

[Mogball]

@stumpOS FYI

[MainRo]

Is there a possible alternative for now? For some tests I would like to iterate over a numpy array (in a for loop).

values = np.random.normal(0.0, 1.0, num_points)
for i in np.nditer(values):
    ...

[lattner]

@stumpOS can you take a look at this?

[stumpOS]

It got deep in my queue. I'll prioritize this for today. Thanks for the ping!

[lattner]

nice, please add to changelog if you haven't already!

[stumpOS]

Yep, PR coming soon