jlanguage

The J programming language, installable with pip. The package also runs J from Python, with J sessions, IPython magics and a Jupyter kernel. This is an unofficial packaging, not affiliated with Jsoftware: J’s home page is jsoftware.com and its official source is jsoftware/jsource. The wheels contain the official J binary releases, unmodified, for Linux (x86_64, aarch64), macOS (Intel and Apple Silicon) and Windows (amd64, arm64).

Usage

Requires Python 3.11 or newer.

pip install jlanguage
jconsole

That starts the standard J console REPL:

   +/ % # 1 2 3 4
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python -m jlang does the same. From Python, jlang.path() returns the J installation directory, containing bin/, system/, addons/ and tools/, and jlang.jconsole_path() the full path of the console.

J from Python and Jupyter

J runs J inside the Python process:

from jlang.core import J
j = J()
j['+/ % # 1 2 3 4']

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In IPython or Jupyter, %load_ext jlang.core adds the %%j and %j magics. Jupyter lists the included J kernel as J. See the J page for sessions, magics and the kernel.

Versioning

The first three numbers of the version are J’s version: jlanguage 9.7.1.1 installs J 9.7.1. The fourth number counts jlanguage’s releases for that J version.

How it’s built

tools/make_wheels.py builds the Python wrapper once, then bundles each official J release from jsoftware.com into its platform wheel. Downloads are checked against the published sha256sums. One CI job packages Linux, macOS and Windows wheels without compilation or platform-specific build runners. The Python interface loads the bundled J library through ctypes. The Jupyter kernel uses kernmini’s Python API.

Contributing

Fetch J for your platform, then install the package and its development tools:

python tools/fetch_j.py
pip install -e '.[dev]'

Edit the notebooks, then run nbdev-export and nbdev-readme to regenerate the Python API and README. Run nbdev-test for the notebooks and pytest for the kernel and packaging tests. python tools/make_wheels.py creates all platform wheels.

License

J is © Jsoftware Inc. and distributed under the GPLv3 (see jsoftware/jsource). This package redistributes the official binaries unmodified.

Releasing a new version

When Jsoftware publishes a new J release:

1. Set version in pyproject.toml to the new J version followed by .1, such as 9.7.2.1. tools/fetch_j.py derives the download URL from it. Check the archive names against the install dir, because the suffixes have changed between releases (9.6.3 used linux64, 9.7.1 uses linux).
2. Commit and push the changes, then run ship-release. CI builds and publishes the five platform wheels.

ship-release tags the version in pyproject.toml and bumps the fourth number afterwards. For another release of the same J version, keep the first three numbers and run ship-release again.