Emacs Elixir syntax checking not working

Questions / Help
,
1

I use Emacs and have the following code in my init.el:

   (use-package elixir-mode
      :ensure t
      :hook (elixir-mode . (lambda ()
                            (add-hook 'before-save-hook 'elixir-format nil t))))

    ;; Alchemist offers integration with the Mix tool.
    (use-package alchemist
      :ensure t
      :hook (elixir-mode . alchemist-mode)
      :delight alchemist-mode)


    (use-package flycheck-mix
      :ensure t
      :init (add-hook 'flycheck-mode-hook #'flycheck-credo-setup))


    (use-package flycheck-credo
      :ensure t
      :defer t
      :init (add-hook 'flycheck-mode-hook #'flycheck-credo-setup))

At the moment I can’t get flycheck syntax checking to work. What am I doing wrong?

1 Like
2

I’m not using use-package, therefore I can only guess.

I can’t see here that you associate flycheck-mode to elixir-mode. So unless you do global-flycheck-mode anywere, you need to (add-hook 'elixir-mode-hook flycheck-mode) at a place where it is appropriate, maybe use-package has some special syntax for it.

PS: Even though I generally prefer emacs over everything else, I currently use VScode for elixir, because language server support is so much better. I hope LS support will be available in alchemist.el soon!

1 Like
3

Yes I do have

(use-package flycheck
  :ensure t
  :delight " ✓"
  :init (global-flycheck-mode))

and I also noticed that I had

(use-package flycheck-mix
  :ensure t
  :init (add-hook 'flycheck-mode-hook #'flycheck-credo-setup))

instead of

(use-package flycheck-mix
  :ensure t
  :init (add-hook 'flycheck-mode-hook #'flycheck-mix-setup))

but that hasn’t solved my problem. I’ll look into VScode as suggested.

4

When you are in an elixir buffer, have you tried M-x flycheck-mix-setup RET?

I’m not sure how :init works in use-package. To be honest, I do not see much sense in it. I prefer a simple helper function which installs packages when required and plain elisp, that makes it much easier to understand what is going on…

5

Okay, I took a closer look at use-packages documentation. As I understand it, :defer t will defer loading the package to the latest point possible, while :init will only be called when the package is loaded, this might mean, that you only add to the hook after it has already been applied.

And again, since I am not using use-package, I’m not sure if I understand the docs correctly, or if I do, how to workaround.

I usually have (add-hook 'flycheck-mode-hook #'flycheck-foo-setup) plain in the config, while I also have (add-hook 'after-init-hook 'global-flycheck-mode) at the toplevel of my config.

This way, I fill up the hook during load time, while postponing the start of flycheck until after init has fully been evaluated.

But maybe, it helps when you add flycheck-credo-setup into elixir-mode-hook? But still, I’m not sure if you should :defer…

6

I’ve made the changes you suggested but unfortunately i’m still not getting any flycheck support for my scripts. Anyway VSCode seems to be doing a much better job for me at the moment so I’ll defer using Emacs for Elixir coding for later when hopefully the tools improve. Thanks again you’ve been very helpful.

7

Make sure you can run credo from command line.
Add credo dependency to mix.exs:

defp deps do
    [
      {:credo, "~> 1.4", only: [:dev, :test], runtime: false}  
    ]

download and run credo:

mix deps.get

mix credo

My emacs setup works fine:

(use-package elixir-mode)

(use-package alchemist-mode
  :ensure alchemist
  :hook elixir-mode
  :bind (:map elixir-mode-map
	      ("s-c" . alchemist-iex-compile-this-buffer)
	      ("C-c C-l" . alchemist-iex-project-run)))

(use-package company
  :init
  (add-hook 'elixir-mode-hook 'company-mode)
  :bind (:map elixir-mode-map
	      ("TAB" . company-indent-or-complete-common)))

(use-package flycheck-mode
  :hook elixir-mode
  :ensure flycheck
  :config
  (use-package flycheck-credo)
  (flycheck-credo-setup))

Also you could try M-x flycheck-verify-setup

It should print something like:

First checker to run:

elixir-credo
- may enable: yes
- executable: Found at /Users/maris/.kiex/elixirs/elixir-1.10.3/bin/mix

8

Thanks @maruks for answering my post. I’ve moved to now using doom-emacs and it’s elixir setup which works okay for my needs. I can therefore not confirm if your solution works for my situation or not. I’ve however made a note and will revert to it should I find the need to role out my own emacs config again. Cheers.

9

Do you use Doom Emacs with Alchemist? If so, does it work well?

10

@dimitarvp yes I do and below is my config:

;; Elixir
(after! lsp-mode
  (defun dap-elixir--populate-start-file-args (conf)
    "Populate CONF with the required arguments."
    (-> conf
        (dap--put-if-absent :dap-server-path `("~/lang_servers/elixir-ls/release/debugger.sh"))
        (dap--put-if-absent :type "mix_task")
        (dap--put-if-absent :name "mix test")
        (dap--put-if-absent :request "launch")
        (dap--put-if-absent :task "test")
        (dap--put-if-absent :taskArgs (list "--trace"))
        (dap--put-if-absent :projectDir (lsp-find-session-folder (lsp-session) (buffer-file-name)))
        (dap--put-if-absent :cwd (lsp-find-session-folder (lsp-session) (buffer-file-name)))
        (dap--put-if-absent :requireFiles (list
                                            "lib/**"
                                            "test/**/test_helper.exs"
                                            "test/**/*_test.exs"))))

  (dap-register-debug-provider "Elixir" 'dap-elixir--populate-start-file-args)
  (dap-register-debug-template "Elixir Run Configuration"
                              (list :type "Elixir"
                                    :cwd nil
                                    :request "launch"
                                    :program nil
                                    :name "Elixir::Run"))

  ;; Enable formatting on save and send reload command to Elixir’s REPL
  (add-hook 'elixir-mode-hook
            (lambda ()
              (add-hook 'before-save-hook 'lsp-format-buffer nil t)
              (add-hook 'after-save-hook 'alchemist-iex-reload-module))))


;; Configure ExUnit package
(use-package! exunit)

;; Disable popup quitting for Elixir’s REPL
(set-popup-rule! "^\\*Alchemist-IEx" :quit nil :size 0.3)

Cheers

1 Like