hack-mode is an Emacs major mode for editing Hack code.

hack-mode includes extensive, precise syntax highlighting:

• Comment highlighting (additionally highlighting special comments like strict, HH_FIXME)
• Keyword highlighting (case insensitive where appropriate)
• String ('foo', "foo", <<<FOO and <<<'FOO') highlighting, including interpolation
• XHP support

It also provides indentation, integration with hackfmt and parenthesis match highlighting.

Install from MELPA, or load this package into your elisp load-path.

After installation, hack-mode will automatically run on .hack, .hck and .hhi files.

It will also run on .php files, but php-mode will take precedence if installed. If you want hack-mode to take precedence, use the following:

(add-to-list 'auto-mode-alist '("\\.php\\'" . hack-mode))

hack-mode provides hack-format-buffer to run hackfmt on the whole file. If you'd like this automatically run on save, add it to your hooks:

(add-hook 'hack-mode-hook #'hack-enable-format-on-save)

We recommend using hack-mode with the following minor-modes:

(add-hook 'hack-mode-hook #'lsp)
(add-hook 'hack-mode-hook #'flycheck-mode)
(add-hook 'hack-mode-hook #'company-mode)

hack-mode is licensed under the GNU General Public License v3.0.