Jupyter::Kernel for Perl 6

This is a pure-Perl 6 implementation of a Perl 6 kernel for Jupyter notebooks.

Jupyter notebooks provide a web-based (or console-based) REPL for running code and serializing input and output.

REALLY QUICK START

mybinder.org provides a way to instantly launch a Docker image and open a notebook. Click 'launch binder' above to start this kernel with a sample notebook. (See below for similar alternatives.)

QUICK START

Installation

You'll need to install zmq. Note that currently, version 4.1 is recommended by Net::ZMQ (though 4.2 is installed by, e.g. homebrew). If you run into stability issues, you may need to downgrade.

brew install zmq           # on OS/X
apt-get install libzmq-dev # on Ubuntu

You'll also want jupyter, for the front end:

pip install jupyter

Finally, install Jupyter::Kernel:

zef install Jupyter::Kernel

At the end of the above installation, you'll see the location of the bin/ directory which has jupyter-kernel.p6. Make sure that is in your PATH.

Server Configuration

To generate a configuration directory, and to install a kernel config file and icons into the default location:

jupyter-kernel.p6 --generate-config

• Use --location=XXX to specify another location.
• Use --force to override an existing configuration.

Client configuration

The jupyter documentation describes the client configuration. To start, you can generate files for the notebook or console clients like this:

jupyter notebook --generate-config
jupyter console --generate-config

Some suggested configuration changes for the console client:

• set kernel_is_complete_timeout to a high number. Otherwise, if the kernel takes more than 1 second to respond, then from then on, the console client uses internal (non-Perl6) heuristics to guess when a block of code is complete.

• set highlighting_style to vim. This avoids having dark blue on a black background in the console client.

Logging

By default a log file jupyter.log will be written in the current directory. An option --logfile=XXX argument can be added to the server configuration file to change this.

Running

Start the web UI with:

jupyter-notebook
Then select new -> perl6.

You can also use it in the console like this:

jupyter-console --kernel=perl6

Or make a handy shell alias:

alias iperl6='jupyter-console --kernel=perl6'

Features

• Autocompletion. Typing [tab] in the client will send an autocomplete request. Possible autocompletions are:

  • methods: after a . the invocant will be evaluated to find methods

  • set operators: after a (, set operators (unicode and texas) will be shown (note the whitespace before the ()).

  • equality/inequality operators: after =, <, or >, related operators will be shown.

  • autocompleting * or / will give × or ÷ respectively.

  • autocompleting ** or a superscript will give you superscripts (for typing exponents).

  • the word 'atomic' autocompletes to the atomic operators. (Use atomic- or atom to get the subroutines with their ASCII names).

  • a colon followed by a sequence of word characters will autocomplete to characters whose unicode name contains that string. Dashes are treated as spaces. e.g. :straw will find 🍓 ("STRAWBERRY") or 🥤 ("CUP WITH STRAW") and :smiling-face-with-smiling-eye will find 😊 ("SMILING FACE WITH SMILING EYES")

• All cells are evaluated in item context. Outputs are then saved to an array named $Out. You can read from this directly or:

  • via the subroutine Out (e.g. Out[3])

  • via an underscore and the output number (e.g. _3)

  • for the most recent output: via a plain underscore (_).

• Magics. There is some support for jupyter "magics". If the first line of a code cell starts with #% or %%, it may be interpreted as a directive by the kernel. See EXAMPLES. The following magics are supported:

  • #% javascript: return the code as javascript to the browser

  • #% html: return the output as html

  • #% latex: return the output as LaTeX. Use latex(equation) to wrap the output in \begin{equation} and \end{equation}. (Or replace "equation" with another string to use something else.)

  • #% html > latex: The above two can be combined to render, for instance, the output cell as HTML, but stdout as LaTeX.

  • %% bash: Interpret the cell as bash. stdout becomes the contents of the next cell. Behaves like Perl 6's built-in shell.

  • %% run FILENAME: Prepend the contents of FILENAME to the contents of the current cell (if any) before execution. Note this is different from the built-in EVALFILE in that if any lexical variables, subroutines, etc. are declared in FILENAME, they will become available in the notebook execution context.

• Comms. Comms allow for asynchronous communication between a notebook and the kernel. For an example of using comms, see this notebook

Docker

This blog post provides a tutorial for running this kernel with Docker. This one describes using mybinder.org.

EXAMPLES

The eg/ directory of this repository has some example notebooks:

• Hello, world.

• Generating an SVG.

• Some unicodey math examples

• magics

SEE ALSO

• Docker image for Perl 6

• iperl6kernel

KNOWN ISSUES

• Definitions of operators are not preserved (see bug 131530).

• Newly declared methods might not be available in autocompletion unless SPESH is disabled (see tests in this PR).

THANKS

Suman Khanal

Matt Oates

Timo Paulssen