[IPython-dev] Jupyter and Other Kernels

[Thomas Kluyver]

I just wanted to chime in and say that I would be ok with having a notion
of startup files in the R kernel, but I have no plans to support magics,
even if someone submits a PR. The code in IPython to parse and transform
magics to valid Python is substantial and tricky to get right, and I don't
want to be stuck supporting similar machinery in R.

I also think there's less need for magics in the notebook. They're a great
interactive convenience in the terminal, but when writing a notebook I
prefer to write regular code, even if it's a bit longer.

Thomas
On 21 Feb 2015 10:41, "John Omernik" <john at omernik.com> wrote:

> Thanks for the info on the magics. I'll think that one through.   Both
> of these issues are interesting in that Kernel devs can be totally
> independent of Jupyter in style (yes they have to follow the API) but
> stylistically, they don't and thus there is not going to be easy
> movement from one kernel to another for users... Not a terrible thing
> and maybe that's fine for most users, but hmm... lots to think about
> here.
>
> Thanks!
>
> On Sat, Feb 21, 2015 at 12:26 PM, Matthias Bussonnier
> <bussonniermatthias at gmail.com> wrote:
> >
> > Le 21 févr. 2015 à 09:04, John Omernik <john at omernik.com> a écrit :
> >
> >> Since the Kernels that are developed for Jupyter look to be different
> >> projects, I am guessing that my question is ok to ask here, but
> >> understand if the response is "not an iPython or Jupyter" question.
> >
> > The question looks fine here.
> >
> >>
> >> I am playing with the iRKernel. https://github.com/takluyver/IRkernel
> >> and have a few questions on how kernels in general interact with
> >> Jupyter (not just IRKernel)
> >>
> >>
> >> 1. Magics: Based on what I am seeing in the iRKernel, Magics appear to
> >> be a "per Kernel" thing rather than a Jupyter thing. Is this correct?
> >> In the iRKernel %lsmagic gets me
> >
> > Yes, they are per-kernel.
> > If you write a python-base one, looks at Doug Blank Metakernel
> > that add some facilities to write magics.
> >
> >>
> >> Error in parse(text = x, srcfile = src): <text>:1:1: unexpected input
> >> 1: %lsmagic
> >
> > As magic are per-kernel, the kernel is responsible to parse them.
> > %lsmagic could be a perfect valid syntax in (perl | php | OCaml | ....)
> > because it is **not** valid syntax in Python, wa can make them magic in
> > IPython.
> >
> >>
> >> So anythoughts on how to implement magics in other kernels if this is
> >> not case? Am I missing something basic here?
> >
> > Depends on your language.
> > Julia decided they did not need magics.
> > For example shell access in julia is with `;`
> > but it's a property of the language.
> >
> > Julia have strings macro, so that can do:
> > matlab"""
> >         (some matlab code)
> > """
> >
> > Ruby have the same.
> >
> > Advice:
> > Pick a syntax that is not valid R. and pre-parse to make it valid R.
> > which is what IPtyhon does.
> >
> >>
> >> 2. So I have a some stuff running in iPython through my
> >> profile_default startup directory.  How do duplicate this so when an R
> >> Kernel starts up, I can have certain imports run all the time etc.  Is
> >> that a kernel specific thing as well?
> >
> > That depends on your kernel.
> > The kernel do whatever it likes.
> > If it want to copy us and run the .r files in .ipython/startup, I
> suppose that would be fine.
> >
> > If we wan another common way of doing things, we can do a working group.
> > But obviously, .py fies are not the right way to configure a R process.
> >
> > --
> > M
> >
> >
> >> Thanks1
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