Automatic language detection for Flyspell

I am always looking for new ways to improve my Emacs experience. Months ago, it happened to my spell-checking configuration thanks to the work of Nicolas Petton.

(defvar mu-languages-ring nil "Languages ring for Ispell")

(let ((languages '("en_GB" "it_IT")))
  (validate-setq mu-languages-ring (make-ring (length languages)))
  (dolist (elem languages) (ring-insert mu-languages-ring elem)))

(defun mu-cycle-ispell-languages ()
  (interactive)
  (let ((language (ring-ref mu-languages-ring -1)))
    (ring-insert mu-languages-ring language)
    (ispell-change-dictionary language)))

This handy code lets me cycle quickly through the languages I need in Flyspell. However, wouldn’t it be easier if Emacs was capable of automatic language detection?

That’s the hole the guess-language package fills.

(use-package guess-language         ; Automatically detect language for Flyspell
  :ensure t
  :defer t
  :init (add-hook 'text-mode-hook #'guess-language-mode)
  :config
  (setq guess-language-langcodes '((en . ("en_GB" "English"))
                                   (it . ("it_IT" "Italian")))
        guess-language-languages '(en it)
        guess-language-min-paragraph-length 45)
  :diminish guess-language-mode)

Notice how I set guess-language-langcodes. It has to be set this way to make guess-language work with my setup for Hunspell.¹

Support for different languages and language detection for multiple languages in the same document are provided out of the box. guess-language is still young, but it’s already making spell-checking in Emacs so much easier.