GoKawiilWhen Emacs 29 made eglot the built-in, default Language Server Protocol (LSP) client, many of us rejoiced.
It is lightweight, fast, adheres strictly to Emacs philosophy, and doesn’t try to reinvent the wheel.
However, being minimal means that when an LSP server steps out of line or acts quirky, eglot doesn’t provide a million customizable toggles to fix it out-of-the-box. Instead, it expects you to leverage the power of Emacs Lisp.
In this post, I will dissect my production-ready eglot setup (part of my heks-emacs configuration) which I use in my day-to-day work, with Scala and Kotlin (and some Java).
For reference, find my full Eglot config here: https://codeberg.org/jjba23/heks-emacs/src/branch/trunk/src/modules/eglot.el
We will walk through basic language setups, specialized workspace configuration handling, and dive deep into some advanced JSON-RPC and advice-based workarounds for Scala (Metals) and Kotlin that make development truly seamless from Emacs and liberate you from IntelliJ ☺️.
It’s not perfect, but it’s pretty darn close to perfection if you ask me, and the developer experience and speed that it enables is just wild. Thank you Emacs, thank you GNU, thank you Eglot! 🐂
Before looking at the code, let’s talk about why we are doing this. For years, the conventional wisdom stated that if you write JVM languages, especially Scala or Kotlin, you must use IntelliJ IDEA. The narrative claimed that these languages are too complex for a standard text editor.
But what do you actually get with IntelliJ? A massive, monolithic Java application that frequently hogs 8GB+ of RAM, locks up your system while “indexing pre-built binaries,” and forces you into a closed proprietary ecosystem.
Emacs turns this paradigm on its head through three core strengths:
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