Ligatures without font-lock

Question

Is there a way to enable ligatures in Emacs other than using font-lock?

I'm asking because font-lock is slow on reasonably large buffers.

After having read it https://www.reddit.com/r/emacs/comments/os6z0d/is_there_support_for_ligatures_in_gnu_emacs/ it seems to me like Emacs is lacking built-in support for ligatures. Afaict, ligatures should be implemented in the font-rendering layer. Am I wrong?

Answer 1

Like a comment on the reddit thread you linked says, Emacs with HARFBUZZ support can use https://github.com/mickeynp/ligature.el (available on Melpa as ligature)

My config for Julia Mono:

(use-package ligature
  :config
  (ligature-set-ligatures '(prog-mode
                            org-mode
                            lsp
                            cc-mode
                            haskell-mode
                            emacs-lisp-mode)
                          '("->" "<-" "-->" "<--" "<-->"
                            "|>" "<|" "=>" "==>" "::"))
  (global-ligature-mode t))