Just FYI, there is an interesting work from particle physics people called Awkward Array for jagged arrays and nested data in general. IIUC, it was initially designed/created in Python (GitHub - scikit-hep/awkward-0.x: Manipulate arrays of complex data structures as easily as Numpy.) and now written in C++ (GitHub - scikit-hep/awkward: Manipulate JSON-like data with NumPy-like idioms.). This Strange Loop talk is a good introduction:
They were talking about using Apache Arrow as a serialization format. I wonder if a similar approach can be uesd in Julia or maybe even have a Awkward Array-compatible reader/writer in Julia. Or create a binding to Awkward Array C++ library? I think it’d be awesome to have something like Awkward Array in Julia.
It’s not an out-of-the-box solution for Julia but I thought it could be a nice food for thoughts.