Private module for the Roc programming language (major mode + lsp support)

[tad-lispy]

Hi! Today I wrote my first Doom module. As far as I can tell it works as intended, but I’d like a review. Especially, after reading Common config anti-patterns, I worry about the performance impact of the LSP part. Below is what I have as of today.

;;; lang/roc/config.el -*- lexical-binding: t; -*-

;; Setup the major mode for roc source files

(define-derived-mode roc-mode fundamental-mode "Roc"
  "Major mode for the Roc programming language")
(add-to-list 'auto-mode-alist
             '("\\.roc\\'" . roc-mode))


;; Setup the LSP support
;; TODO: Is this the right way to set up the server? Am I hindering Doom's performance?
;; See https://discourse.doomemacs.org/t/common-config-anti-patterns/119#loading-packages-too-early-3
(if (and
     (modulep! :tools lsp)
     (modulep! :lang roc +lsp))
    (use-package! lsp-mode
      :config
      (progn
        (add-to-list 'lsp-language-id-configuration '(roc-mode . "roc"))
        (lsp-register-client (make-lsp-client :new-connection (lsp-stdio-connection "roc_ls")
                                              :activation-fn (lsp-activate-on "roc")
                                              :major-modes '(roc-mode)
                                              :server-id 'roc_ls))
        (add-hook 'roc-mode-local-vars-hook #'lsp!))))

You can also see the same code in context of my whole system configuration. I will be pushing eventual updates there.

What are you trying to do?

It’s working as intended

When I visit any .roc file, Emacs sets the major mode to roc-mode and connects to the language server (starting it if necessary). The code assumes that roc_ls program is installed (I provide language servers on a per-project basis, see here for example https://gitlab.com/tad-lispy/roc-language-playground/-/blob/31b53052f24666d85ef8fc035f1f92c5006fb49c/flake.nix#L21).

I consider myself a novice at Emacs Lisp, so I will appreciate any constructive feedback.