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Atom language syntax highlighting for z/VM | Blog

Meet ATOM, one of Open Mainframe Project’s Oldest Projects

By | February 18, 2021

Walter Church, Owner of Open Mainframe Project’s Atom Syntax Highlighter

The Atom editor is a robust tool that allows great integration of many different packages. This allows developers to create “pug-ins” to fit any of their needs. One common feature that almost all modern editors posses is syntax highlighting. This is where different parts of the code shows up in different colours to help the developer more easily make out what the code structure looks like. For example, command or instruction words may be highlighted in a specific colour to easily spot them in the code. Comments are another common area of code that get highlighted in a different colour to easily distinguish that the section is not code.

This is where the Open Mainframe Project fits in. The Atom Syntax Highlighter project is a way to add syntax highlighting to IBM’s High Level Assembler files as well as IBM’s PL/X language. This allows developers that use Atom as an editor to take advantage of the syntax highlighting to more easily read the code. You can find the Atom packages from the Open Mainframe Project here:


The future work for the Atom Syntax Highlighter is to continue to add more functionality to the different supported languages. Currently the focus is on Z assembler and PL/X, but there are also packages for REXX and SCRIPT files. The focus is to allow developers to visually identify code. This helps to differentiate instructions, operands, comments, etc.

There is also work needed to be done in writing code snippets to test the syntax highlighting. This provides test cases to ensure that the syntax highlighters are working correctly. These code snippets help test our edge cases and to catch if changes made to the syntax highlighter are working correctly. These code snippets also need to align with proper language conventions, as well as a mix of breaking conventions to determine if the syntax highlighter catches mistakes as well as correctly highlights the code.


This appears to be a very good year for the Atom Syntax Highlighting project. There is plenty of exciting work still to be done with the project. Another exciting opportunity is that there may be a mentorship through the Linux Foundation this year. If you’re interested, fill out this Mentorship form by March 31:

Anyone interested in the source code for the Atom packages can also find it on github: