This update of the Kotlin kernel for Jupyter Notebook primarily targets library authors and enables them to easily integrate Kotlin libraries with Jupyter notebooks. It also includes an upgrade of the Kotlin compiler to version 1.5.0, as well as bug fixes and performance improvements.

The old way to add library integrations

As you may know, it was already possible to integrate a library by creating a JSON file, which we call a library descriptor. In the kernel repository, we have a number of predefined descriptors. You can find the full list of them here.

Creating library descriptors is rather easy. Just create a JSON file and provide a description section with a library description and a link section with a link to the library’s web page. Then add the repositories and dependencies sections, describing which repositories to use for dependency resolution and which artifacts the library includes. You can also add an imports section, where you list imports that will be automatically added to the notebook when the descriptor is loaded, such as init and initCell code snippets, renderers, and so on. When you are finished, save the created file and refer to it from the kernel in whatever way is most convenient for you. In this release, we’ve added some more ways to load descriptors. You can read more about how to create library descriptors here.

This method for integrating libraries is still supported and works particularly well when you are not the author of the library you want to integrate. But it does have some limitations:

1. It requires additional version synchronization. The integration breaks if a new version of the library is released and a class that was used in the integration is renamed.
2. It’s not that easy to write Kotlin code in JSON without any IDE support. So if your library provides renderers or initialization code, then you have to go through a potentially long process of trial and error.
3. Transitive dependencies are not supported. If libraries A and B provide descriptors and library A depends on library B, then adding just the descriptor for library A is not enough, and you also need to run %use B.
4. Advanced integration techniques are not allowed. See below for more info.

#kotlin