For one, Grumpy only supports Python’s older Python 2.x syntax, ... Without C extensions, only the most vanilla Python scripts can be compiled and run under the current interation of Grumpy.

But writing everything in vanilla Python is excellent for learning the ins and outs of deep learning. [Read: How Polestar is using blockchain to increase transparency ] ...

Generally, the more the app relies on “vanilla” Python, the more likely it will run on PyPy without modification. However, taking best advantage of PyPy may require testing and study.