dotfiles/emacs-lisp/lsp.org

:PROPERTIES:
:ID:       cc668372-8d95-461b-a7c6-3e2b51de3f40
:END:
#+title: LSP
#+filetags: emacs-load

# SPDX-FileCopyrightText: 2022 Richard Brežák <richard@brezak.sk>
#
# SPDX-License-Identifier: LGPL-3.0-or-later

Disable server downloading suggestions.

#+begin_src emacs-lisp
  (setq lsp-enable-suggest-server-download nil)
#+end_src

* Python

Using the Microsoft language server as it's the best afaik. It's weird because it doesn't lookup the path to itself via PATH but has to be statically set.

#+BEGIN_SRC emacs-lisp
  (defun magic_rb/locate-python-executable-lsp-deffered ()
    "Locates the python executable available to the current buffer and only then calls `lsp-deferred'."
    (lambda ()
      (require 'lsp-python-ms)
      (envrc-mode)
      (setq-local lsp-python-ms-executable (executable-find "python-language-server"))
      (lsp-deferred)))

  (use-package lsp-python-ms
    :straight t
    :after (lsp-mode)
    :hook (python-mode . magic_rb/locate-python-executable-lsp-deffere)
    :config
    (defvar-local lsp-python-ms-executable ""))
#+END_SRC

* C/C++

This just requires hooking lsp onto ~c-mode~ and ~c++-mode~.

#+BEGIN_SRC emacs-lisp
  (use-package lsp-c++-c
    :no-require t
    :after (lsp-mode)
    :hook ((c-mode-hook c++-mode-hook) . lsp-deferred))
#+END_SRC

* Haskell

Enable ~haskell-mode~, and ~lsp-haskell~

#+BEGIN_SRC emacs-lisp
  (use-package haskell-mode
    :straight t
    :hook
    (((haskell-mode haskell-literate-mode) . interactive-haskell-mode)
     ((heskell-mode haskell-literate-mode) . haskell-indentation-mode))
    :config
    (setq lsp-haskell-plugin-ghcide-type-lenses-global-on nil
          lsp-haskell-plugin-import-lens-code-lens-on nil))
  (use-package lsp-haskell
    :straight t
    :after (haskell-mode lsp-mode)
    :hook ((haskell-mode haskell-literate-mode) . lsp-deferred))
#+END_SRC

Disable the ~haskell-stack-ghc~ flycheck checker, it's not used when lsp starts, but it does get loaded just before it. Loading and unloading it is slow and causes Emacs to freeze for a few seconds, so just disable it.

#+BEGIN_SRC emacs-lisp
  (with-eval-after-load "flycheck"
    (add-to-list 'flycheck-disabled-checkers 'haskell-stack-ghc))
#+END_SRC

* Javascript

Enable ~rjsx-mode~ instead of ~javascript-mode~ or ~js2-mode~ as it properly handles inline HTML.

#+BEGIN_SRC emacs-lisp
   (use-package rjsx-mode
     :straight t
     :config
     :mode ("\\.js\\'" . rjsx-mode)
     :mode ("\\.jsx\\'" . rjsx-mode)
     :hook (rjsx-mode . lsp-deferred)
     :init
     ;; Originally this function exits with a call to `error`, which causes the simple "PATH lookup"
     ;; scheme to not be tried
     (cl-defun lsp--npm-dependency-path (&key package path &allow-other-keys)
       "Return npm dependency PATH for PACKAGE."
       (let ((path (executable-find
                    (f-join lsp-server-install-dir "npm" package
                            (cond ((eq system-type 'windows-nt) "")
                                  (t "bin"))
                            path))))
         (unless (and path (f-exists? path))
           nil)
         path)))
#+END_SRC

* Typescript

Enable ~typescript-mode~ for =.ts=, =.tsx= and hook ~lsp-mode~ on it. It doesn't specifically support inline HTML,
but aside from minor indentation issues it works fine.

#+BEGIN_SRC emacs-lisp
  (use-package typescript-mode
    :straight t
    :config
    :mode ("\\.ts\\'" . typescript-mode)
    :mode ("\\.tsx\\'" . typescript-mode)
    :hook (typescript-mode . lsp-deferred))
#+END_SRC

* HTML Markup Language

Enable ~web-mode~ for =.html=, =.xhtml= and hook ~lsp-mode~ on it.

#+BEGIN_SRC emacs-lisp
  (use-package web-mode
    :straight t
    :mode ("\\.html\\'" . web-mode)
    :mode ("\\.xhtml\\'" . web-mode)
    :hook (web-mode . lsp-deferred))
#+END_SRC

* CSS Style Sheet Language

Enable ~css-mode~ for =.css=, =.scss= and hook ~lsp-mode~ on it. Also make ~flycheck~ happy.

#+BEGIN_SRC emacs-lisp
  (use-package css-mode
    :mode ("\\.css\\'" . css-mode)
    :mode ("\\.scss\\'". css-mode)
    :hook (css-mode . lsp-deferred)
    :config
    (with-eval-after-load "flycheck"
      (flycheck-add-mode 'javascript-eslint 'web-mode)))
#+END_SRC