Ocaml-eglot Loads Eglot For All Files: Issue & Fix

Nov 9, 2025 by Admin 51 views

ocaml-eglot Eagerly Loads Eglot for All Files: Discussion and Solution

Hey everyone! Let's dive into a peculiar issue some of us have been encountering with ocaml-eglot. It seems that after installing ocaml-eglot, Eglot gets loaded automatically when opening any file, not just OCaml files. This can be a bit of a drag, especially when you're working on projects that aren't related to OCaml.

The Problem: Eglot Loading Globally

The main issue is that Eglot loads automatically even when you're opening files like your init.el or other non-OCaml source files. This happens without you explicitly requiring or enabling ocaml-eglot in your Emacs configuration. Simply installing it via package.el is enough to trigger this behavior. Let's break down why this is happening and how we can fix it.

Steps to Reproduce

If you want to see this in action, here’s how you can reproduce the issue:

Start Emacs with a minimal configuration. This means you should have a basic init.el that includes (package-initialize) but doesn't explicitly require ocaml-eglot.
```
(package-initialize)
;; ocaml-eglot is installed but not required anywhere
```
Open any file that isn’t an OCaml source file. For example, your ~/.emacs.d/init.el is a good candidate.
Run (featurep 'eglot) in the *ielm* buffer. You’ll see that it returns t, indicating that Eglot is loaded.

Expected Behavior

Ideally, Eglot (and by extension, ocaml-eglot) should only be loaded when you're working with OCaml buffers. This means it should kick in when you're in tuareg-mode or caml-mode, which are the major modes for OCaml development in Emacs. This keeps things clean and prevents unnecessary loading of Eglot in non-OCaml projects.

Actual Behavior

What's actually happening is that ocaml-eglot's autoloads install ocaml-eglot-objinfo-handler on find-file-hook. This hook runs every time you open a file. The handler then calls (require 'ocaml-eglot-util), which in turn requires Eglot. This is why Eglot ends up loading globally, regardless of the file type you're opening. It's like bringing a toolbox to a picnic – handy sometimes, but not always necessary!

Backtrace Excerpt

To give you a clearer picture, here’s a snippet of the backtrace when Eglot loads:

find-file -> find-file-hook -> ocaml-eglot-objinfo-handler
  -> require ocaml-eglot-util -> require eglot

This shows the chain of events that leads to Eglot being loaded. The find-file function triggers the find-file-hook, which then calls our culprit: ocaml-eglot-objinfo-handler. This handler's requirement of ocaml-eglot-util ultimately pulls in Eglot.

The Suggested Fix: Restricting the Handler

Okay, so how do we solve this? The most straightforward solution is to restrict ocaml-eglot-objinfo-handler to only run in OCaml major modes. This ensures that Eglot is only loaded when you're actually working with OCaml files. There are a couple of ways to achieve this.

Method 1: Using Mode-Specific Hooks

One approach is to add the handler to the hooks for tuareg-mode and caml-mode. This ensures that the handler is only active when you're in these modes.

(add-hook 'tuareg-mode-hook #'ocaml-eglot-objinfo-handler)
(add-hook 'caml-mode-hook   #'ocaml-eglot-objinfo-handler)

This code snippet adds ocaml-eglot-objinfo-handler to the tuareg-mode-hook and caml-mode-hook. This means that whenever you enter tuareg-mode or caml-mode, the handler will be activated. This is a clean and effective way to ensure that Eglot is only loaded when needed.

Method 2: Conditional Execution

Another way to achieve the same result is to use a conditional statement that checks the current major mode before running the handler.

(when (derived-mode-p 'tuareg-mode 'caml-mode)
  ...etc...)

This code uses derived-mode-p to check if the current mode is either tuareg-mode or caml-mode. If it is, then the code inside the when block will be executed. This is another way to ensure that the handler only runs in the appropriate modes. It’s like having a gatekeeper that only lets the handler through when the conditions are right.

Additional Notes and Observations

It's worth noting that the package’s autoloads seem to be the root cause of the global hook installation. If you remove ocaml-eglot-objinfo-handler from find-file-hook after startup, you can prevent Eglot from loading when visiting non-associated files. This can be a temporary workaround while a more permanent solution is implemented.

Real-World Impact and Benefits

By implementing this fix, Emacs users can experience a more streamlined and efficient development environment. Loading Eglot only when necessary reduces startup times and memory usage, especially for those working on multiple projects with different language requirements. It's about keeping your tools sharp and focused on the task at hand.

Imagine you're juggling multiple projects – one in OCaml and another in Python. Without this fix, Eglot would load every time you open any file, even Python scripts. This is like bringing your entire set of power tools when all you need is a screwdriver. By restricting Eglot to OCaml buffers, you keep your Emacs lean and mean, loading only what's necessary for the task at hand.

This improvement also translates to a more responsive and less resource-intensive Emacs experience. Nobody wants to wait for unnecessary processes to load, especially when you're in the middle of a coding frenzy. By preventing Eglot from loading globally, you ensure that Emacs stays snappy and responsive, allowing you to focus on your code without distractions.

Furthermore, this fix aligns with the principle of least privilege – only load what you need, when you need it. This is a fundamental concept in software development and system administration, ensuring that resources are used efficiently and security risks are minimized. By applying this principle to Emacs and ocaml-eglot, we create a more robust and user-friendly development environment.

Environment Details

For those curious about the environment where this issue was observed, here are the details:

Emacs version: 30.2
ocaml-eglot installed via Melpa
Package-Version: 20251106.1948
Package-Revision: f7ea764c5b1d
OS: macOS 15.6.1

If you're experiencing this issue, knowing the environment details can help in troubleshooting and verifying the fix.

Conclusion: Keeping Eglot Focused

In summary, the issue of ocaml-eglot eagerly loading Eglot for all files can be a bit of a nuisance. However, by understanding the root cause and implementing the suggested fix, we can ensure that Eglot is only loaded when working with OCaml buffers. This leads to a more efficient and streamlined Emacs experience. So, give those fixes a try, and let's keep our Emacs environments running smoothly! Happy coding, guys!

By restricting ocaml-eglot-objinfo-handler to OCaml major modes, we prevent unnecessary loading and keep our Emacs focused on the task at hand. It’s a small change that makes a big difference in the overall development experience. If you've been struggling with this issue, give the suggested fix a try and see how it improves your Emacs workflow.