JETLS.jl

What the language server aims to do

JETLS is a project to build a new language server for Julia. The README states the goal is to develop the server, currently called JETLS, and to improve developer productivity with advanced static analysis and integration with the Julia runtime. It builds on existing tooling, specifically JET.jl for type inference based analysis, JuliaSyntax.jl for parsing, and JuliaLowering.jl for working with lowered code. Using those pieces, JETLS aims to offer features such as type sensitive diagnostics and macro aware go to definition. The repository manages two things. The first is JETLS.jl, a Julia package that implements the language server. The second is jetls-client, a sample VSCode extension that acts as a language client for testing JETLS. The README carries two warning notes. The first says JETLS is experimental, under active development, not production ready, and that APIs and behavior may change, with limited stability and performance and expected bugs. The second says JETLS supports Julia 1.12.2 through 1.13, and it does not support Julia 1.12.1 or earlier, nor Julia 1.14 or newer or nightly builds. The README also shows a code coverage badge and a continuous integration badge, and it points readers to the linked user guide for installation, configuration, and feature details. Those version bounds are important because they define exactly which Julia releases the server will run against.

How to use and build it

For end users, the README points to a user guide documentation site for installation instructions, configuration options, and feature guides rather than repeating those steps inline. The development notes section points contributors to DEVELOPMENT.md for developer notes and AGENTS.md for specific coding rules, which the README recommends that human developers read as well. Meta level discussions, research, and ideas about JETLS development are compiled as Obsidian notes published at a linked site. Because the project is experimental, a reader should expect the setup and feature set to shift, and the user guide is the place the maintainers keep current instructions. The companion jetls-client VSCode extension is described as a sample client used to test JETLS, so it serves as a reference for how an editor connects to the server. The README does not include a copy paste build command in the text provided, so the practical build steps live in the linked guides and the repository's own development files. The explicit support window of Julia 1.12.2 through 1.13 means a user must be on one of those versions to try the server, and the warning against 1.14 and nightly is a deliberate boundary rather than a temporary gap. The README itself is short, so the linked guides and the repository's own files carry the operational detail a contributor needs.

License and project status

The license is MIT, as stated in the README and in LICENSE.md. The project is maintained under the aviatesk organization on GitHub, and the README links to the package repository, the user guide, the Obsidian development notes, and the VSCode client. The README's badge row advertises the MIT license, a user guide built with the Julia documentation tooling, and a dev notes site, which together are the main public faces of the project. The status warnings are the most important practical information: JETLS is not production ready, its APIs and behavior may change, and its stability and performance are limited, so it is best treated as a tool for testing and feedback rather than for daily development. The supported Julia range, 1.12.2 through 1.13, is narrow by design, and the README is explicit that 1.12.1 and earlier as well as 1.14 and nightly are not supported. For someone evaluating the tool, the combination of an MIT license, a clear experimental label, and a fixed Julia version window gives a realistic picture of where the project stands. The feature goals, type sensitive diagnostics and macro aware navigation, are aimed at problems that Julia developers hit when working with metaprogramming and complex type hierarchies, and the project leans on established Julia packages for parsing and analysis rather than building those layers from scratch.

Editorial conclusion

JETLS is an experimental Julia language server licensed under MIT. The README states it supports Julia 1.12.2 through 1.13 and is not production ready, with APIs and behavior subject to change.