Numbat mode for Emacs

numbat-ts-mode.el

(define-derived-mode numbat-ts-mode prog-mode "Numbat[ts]"
  "Major mode for editing Numbat source code wtih tree-sitter."
  (setq-local font-lock-defaults nil)
  (when (treesit-ready-p 'numbat)
    (treesit-parser-create 'numbat)
    (numbat-ts-setup)))

(defun numbat-ts-setup ()
  "Set up treesit for numbat-ts-mode"
  (setq-local treesit-font-lock-feature-list
              '((string)
                (func var unit dimension cond decorator module_import)
                (boolean)))
  (setq-local numbat-ts-font-lock-rules
              '(:language numbat :override t
                :feature string
                ((string) @font-lock-string-face)

                ;; :language numbat :override t
                ;; :feature comment
                ;; ((:match "^[ \t]#.*$" @font-lock-comment-face))

                :language numbat :override t
                :feature func
                ((function_decl
                  "fn" @font-lock-keyword-face
                  (identifier) @font-lock-function-name-face
                  ("<"
                   (identifier) @font-lock-type-face
                   ">") :?
                  "("
                  (identifier) @font-lock-variable-name-face
                  (dimension_expr) :? @font-lock-type-face
                  (type_annotation) :? @font-lock-type-face
                  ;;"where" :? @font-lock-keyword-face
                  ))

                :language numbat :override t
                :feature var
                ((variable_decl
                  "let" @font-lock-keyword-face
                  (identifier) @font-lock-variable-name-face
                  ":" :?
                  (type_annotation) :? @font-lock-type-face))

                :language numbat :override t
                :feature cond
                ((condition
                  "if" @font-lock-keyword-face
                  "then" @font-lock-keyword-face
                  "else" :? @font-lock-keyword-face))

                :language numbat :override t
                :feature unit
                ((unit_decl
                  "unit" @font-lock-keyword-face
                  [(identifier) @font-lock-variable-name-face ; apparently parse failure
                   (dimension_expr) :? @font-lock-type-face]
                  ))

                :language numbat :override t
                :feature dimension
                ((dimension_decl
                  "dimension" @font-lock-keyword-face
                  (identifier) @font-lock-type-face))

                :language numbat :override t
                :feature boolean
                ((boolean) @font-lock-constant-face)

                :language numbat :override t
                :feature decorator
                ((decorator) @font-lock-constant-face
                 ("("
                  (identifier) @font-lock-variable-name-face
                  (":"
                   "short" @font-lock-keyword-face) :?
                  ")") :?)

                :language numbat :override t
                :feature module_import
                ((module_import) "use" @font-lock-keyword-face))
              )
  (setq-local treesit-font-lock-settings
              (apply #'treesit-font-lock-rules
                     numbat-ts-font-lock-rules))
  (treesit-major-mode-setup))

(provide 'numbat-ts)