IPython native kernel missing?

[Ricardo Wurmus]

Hi Guix,

I’m trying to package Jupyter (an improved version of IPython, from what
I’ve heard) and noticed that the tests for jupyter-client fail because
the native “python3” (or “python2”) kernel cannot be found.  According
to the documentation, this “kernel” should always be available and
doesn’t need to be installed.

Looking around in the sources of python-ipython (an input to the Jupyter
packages I’m working on) I see that this file

    $out/lib/python2.7/site-packages/IPython/kernel/kernelspec.py

contains hard-coded system paths:

    SYSTEM_KERNEL_DIRS = ["/usr/share/jupyter/kernels",
                          "/usr/local/share/jupyter/kernels",
                         ]

Yet I have not found any directory named “kernels” in the output of the
python-ipython package.  Nor have I found any “kernel.json” files.  It
seems to me that IPython should install at least the native kernel at
some point, but currently doesn’t seem to include it.

I would like to fix this, but I really don’t know anything about IPython
and I don’t even know what the word “kernel” describes in this context.
Could someone with an understanding of IPython please take a look at
this?

~~ Ricardo