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The J code wiki is organized into the following sections.

Everyone is free to contribute. Before doing so, please read the guidelines for editing.


J Application Library (JAL) is the extensibility platform for J programming systems, consisting of the core system library and addons contributed by J users. It features online package updating from this web portal with addon documentation, source versioning, build and distribution systems.

JAL replaces the earlier Packages wiki pages.


A script file can contain anything from a single utility up to a complete application.

It should be self-contained, so that when loaded, it reads in any required library scripts.

Scripts can be installed anywhere in your system. A convenient place for scripts is the misc subdirectory of addons. For example, after installing myscript.ijs, it would be available as:

   jpath '~addons/misc/myscript.ijs'

To contribute a script, make an entry in the Scripts page and then create the page. The page name should be prefixed by Scripts, for example: Scripts/TrigExplorer.

You can take ownership of a script page, so that only you have the ability to change it, see Owned Pages.

To create a downloadable attachment containing the script, insert the tag attachment:attachment-name somewhere in your page. When the page is saved, it prompts you to upload the file. You can look at the attachments to a page from the More Actions dropdown box on the page. For example:



These are short J expressions that are useful in their own right and can be cut & pasted into your programs.

A typical example has some introductory text, and code sections with phrases and examples. For a typical layout, see page Indices as Base.

To contribute a phrase, make an entry in the appropriate subpage of Phrases.

Note: the Phrases section supersedes the earlier J Phrases book. The expository material in the latter is not appropriate here, and instead is included in the wiki Essays or Guides sections.

Work in Progress

This contains any pages with work in progress.