New erlang (treesitter) mode

[dgud]

Brief summary of what the package does

New erlang (treesitter) mode

Currently only fixes font-locking and relies on the "old" erlang mode for everything else.

Direct link to the package repository

https://github.com/erlang/emacs-erlang-ts

Your association with the package

maintainer, author

Relevant communications with the upstream package maintainer

None needed

Checklist

• The package is released under a GPL-Compatible Free Software License
• I've read CONTRIBUTING.org
• ** I've used the latest version of package-lint to check for packaging issues, and addressed its feedback
• My elisp byte-compiles cleanly
• I've used M-x checkdoc to check the package's documentation strings
• I've built and installed the package using the instructions in CONTRIBUTING.org

** package-lint reports errors for function names but they are intentionally there for overriding the
the erlang mode functions.

[riscy]

Thanks for this. Quick first pass -

⸺ erlang-ts.el with package-lint 20250108.1407:

5 issues found:
26:19: warning: "" is not a valid version. MELPA will handle this, but other archives will not.
71:0: error: "erlang-font-lock-level-1" doesn't start with package's prefix "erlang-ts".
76:0: error: "erlang-font-lock-level-2" doesn't start with package's prefix "erlang-ts".
81:0: error: "erlang-font-lock-level-3" doesn't start with package's prefix "erlang-ts".
86:0: error: "erlang-font-lock-level-4" doesn't start with package's prefix "erlang-ts".

It's probably a good idea to add a version, and I see you commented:

package-lint reports errors for function names but they are intentionally there for overriding the the erlang mode functions.

and I see from your code that this is "So the menus (and functions) work as expected". I think yours is the only ts package I've seen that had this requirement, and I usually try to be pretty intolerant about people dipping their toes outside their namespaces - even a closely related one like this.

Could you describe what's going on that's causing the functions (which?) to work unexpectedly?

[dgud]

It's probably a good idea to add a version

Hmm, ok, maintaining the "old" erlang mode for 15 years, and there the version have been updated,
maybe twice.
So I thought it would be better if it was updated by the package-manager.

Could you describe what's going on.

I don't have time to completely re-write all the functionality from the old mode in the new erlang-ts mode now,
I will do that bit by bit when time permits.

So erlang-ts mode (currently) loads and re-uses the old erlang mode for everything except syntax-highlighting which
is overloaded via the treesitters font-lock functionality.

The old erlang mode installs menus where the user can change syntax-highlighting level, those menu entries call
erlang-font-lock-level-X functions which I have overloaded in the erlang-ts mode so the user can change syntax-highlighting level from the menu even when using erlang-ts mode.

I'm not emacs-lisp guy, just a user and the unlucky guy in the maintaining lottery :-)
do you have better suggestion of how overload the functionality?

[riscy]

So I thought it would be better if it was updated by the package-manager.

That's fair - I think some people even just leave it at version 0.0. My only (weak) counter would be that I guess people sometimes find elisp files lurking on wikis and old archives, and in that case seeing the versions could be interesting (if not that useful). I would recommend avoiding :version-regexp in your recipe - semantic versioning should be easily parsed by the package-build machinery.

do you have better suggestion of how overload the functionality?

I understand the time constraint (and thank you, btw, for your maintainership). I think a better pattern would be to create advice functions inside your namespace:

(defun erlang-ts--font-lock-level-1 (func &rest args)
  "To be used as :around advice."
  (if erlang-ts-mode
      (erlang-ts-set-font-lock-level 1)
    (apply func args)))

Then, the first time your mode is toggled on, you could run:

(advice-add #'erlang-font-lock-level-1 :around #'erlang-ts--font-lock-level-1)

(this is idempotent so it's okay if it gets called repeatedly)

Finally, I'd recommend you add a erlang-ts-unload-function function so that if a user did run unload-feature (q.v.) the advice would be removed too, using:

(advice-remove #'erlang-font-lock-level-1 #'erlang-ts--font-lock-level-1)

[dgud]

I have added (and tagged) a version 0.1 last week,

I will test your other suggestion next week, need to read up emacs-lisp a bit.

Thanks for taking time and making suggestions of how to solve it.

[dgud]

To be able to get rid of all warnings I had to do:

(defun erlang-ts--font-lock-level-1 (func &rest args)
  "To be used as :around advice.
FUNC with ARGS will be called if `erlang-ts-mode' is not active."
  (if (derived-mode-p 'erlang-ts-mode)
      (erlang-ts-set-font-lock-level 1)
    (apply func args)))

And I also added a unload function

(defun erlang-ts-unload-function ()
  "Used by `unload-feature'."

  (while (rassoc 'erlang-ts-mode auto-mode-alist)
    (setq auto-mode-alist
          (assq-delete-all (car (rassoc 'erlang-ts-mode auto-mode-alist))
                           auto-mode-alist)))

  (advice-remove #'erlang-font-lock-level-1 #'erlang-ts--font-lock-level-1)
  (advice-remove #'erlang-font-lock-level-2 #'erlang-ts--font-lock-level-2)
  (advice-remove #'erlang-font-lock-level-3 #'erlang-ts--font-lock-level-3)
  (advice-remove #'erlang-font-lock-level-4 #'erlang-ts--font-lock-level-4))

And things seems to work as expected.

[riscy]

Thanks! Here's the latest (maybe your default branch wasn't updated? Also I want to emphasize that the version-regexp is probably not required).

⸺ erlang-ts.el with package-lint 20250108.1407:

4 issues found:
71:0: error: "erlang-font-lock-level-1" doesn't start with package's prefix "erlang-ts".
76:0: error: "erlang-font-lock-level-2" doesn't start with package's prefix "erlang-ts".
81:0: error: "erlang-font-lock-level-3" doesn't start with package's prefix "erlang-ts".
86:0: error: "erlang-font-lock-level-4" doesn't start with package's prefix "erlang-ts".

⸺ erlang-ts.el with melpazoid:

- `;;; Commentary` is much wider than 80 characters

⸺ Package and license:

• Avoid :version-regexp in recipes except in unusual cases
• In case you haven't, ensure GitHub release v0.1 is up-to-date with your current code and Package-Version

[dgud]

Check again, I had pushed to my "private" repo and not the official/upstream one, sigh.

Pushed it to upstream now.

Avoid :version-regexp in recipes except in unusual cases

What does that mean, that you want use the github tag?

In case you haven't, ensure GitHub release v0.1 is up-to-date with your current code and Package-Version

I will tag the release when you are happy :-)

[riscy]

What does that mean, that you want use the github tag?

Your recipe is

(erlang-ts
    :fetcher github
    :repo "erlang/emacs-erlang-ts"
    :version-regexp "v%v")

but :version-regexp is probably not necessary to specify here since you're already following a convention that package-build can figure out.