mlx-mode

Emacs major mode for editing MLX files — OCaml with JSX syntax.

Features

• Syntax highlighting for JSX tags, components, attributes, and delimiters
• Full OCaml highlighting via tuareg-mode
• JSX-aware indentation
• LSP support via eglot + ocamllsp

Prerequisites

opam install mlx ocamlmerlin-mlx ocamlformat-mlx

Your dune-project must declare the MLX dialect with the merlin reader:

(dialect
 (name mlx)
 (implementation
  (extension mlx)
  (merlin_reader mlx)
  (preprocess
   (run mlx-pp %{input-file}))))

Installation

Doom Emacs

In ~/.config/doom/packages.el:

(package! mlx-mode
  :recipe (:host github :repo "ocaml-mlx/emacs-mlx"))

In ~/.config/doom/config.el:

(use-package! mlx-mode
  :mode "\\.mlx\\'"
  :hook (mlx-mode . eglot-ensure))

Then run doom sync and restart Emacs.

use-package (straight.el)

(use-package mlx-mode
  :straight (:host github :repo "ocaml-mlx/emacs-mlx")
  :mode "\\.mlx\\'"
  :hook (mlx-mode . eglot-ensure))

Manual

Clone this repository and add it to your load-path:

(add-to-list 'load-path "/path/to/emacs-mlx")
(require 'mlx-mode)

;; Auto-start eglot for .mlx files (optional)
(add-hook 'mlx-mode-hook #'eglot-ensure)

lsp-mode (alternative to eglot)

If you use lsp-mode instead of eglot, just ensure ocamllsp is in your PATH and add:

(add-hook 'mlx-mode-hook #'lsp)

LSP

mlx-mode automatically registers ocamllsp with both eglot and lsp-mode. You only need to start your preferred LSP client, either via a hook (as shown above) or manually with M-x eglot / M-x lsp.

Customization

Variable	Default	Description
mlx-jsx-indent-offset	2	Indentation for JSX children

Faces

• mlx-jsx-tag-face — lowercase tags (div, span)
• mlx-jsx-component-face — uppercase components (App, Module.View)
• mlx-jsx-attribute-face — attribute names (className, onClick)
• mlx-jsx-delimiter-face — delimiters (<, </, />)

Related projects

• mlx — the MLX preprocessor
• ocaml_mlx.nvim — Neovim plugin for MLX
• tree-sitter-mlx — Tree-sitter grammar for MLX
• tuareg — OCaml mode for Emacs

License

MIT