ppl-mode.el

(require 'tree-sitter)
(require 'tree-sitter-hl)

(defvar ppl--base-dir
  (file-name-directory load-file-name)
  "Directory containing this file.")

(define-derived-mode ppl-mode prog-mode "PPL"
  "Major mode for editing PPL files."
  (setq tree-sitter-language (tree-sitter-require 'ppl))
  (setq tree-sitter-hl-default-patterns
        (with-temp-buffer
          (insert-file-contents (concat ppl--base-dir "queries/highlights.scm"))
          (buffer-string))))

;;;###autoload
(progn
  (add-to-list 'auto-mode-alist '("\\.ppl\\'" . ppl-mode)))

(provide 'ppl-mode)