:title: Treesitter
:date: 2026-01-18
:tags:
:identifier: 20260118T133600
:signature: 5=10

Treesitter
==========

.. seealso::

   `How To Get Started with Tree Sitter <https://www.masteringemacs.org/article/how-to-get-started-tree-sitter>`__
      Article on Matering Emacs

   `Combobulate: Structured Movement and Editing with Tree-Sitter <https://www.masteringemacs.org/article/combobulate-structured-movement-editing-treesitter>`__
      Another introducing the ``combobulate`` package

As of version ``29.1`` Emacs comes with support out of the box (assuming it has been compiled with the ``--with-tree-sitter`` flag)

.. code-block:: elisp
   :project: emacs
   :filename: init.el

   (use-package alc-treesitter
     :load-path "lisp"
     :if (treesit-available-p))

Installing Grammars
^^^^^^^^^^^^^^^^^^^

While Emacs supports the tree-sitter library itself, it does not come with any grammars which need to be installed separately.
Thankfully, Emacs does provide a few utilities to help with this

.. code-block:: elisp
   :project: emacs
   :template: elisp-module
   :filename: lisp/alc-treesitter.el

   (setq treesit-language-source-alist
         '((python "https://github.com/tree-sitter/tree-sitter-python" "v0.20.4")
           (typescript "https://github.com/tree-sitter/tree-sitter-typescript" "v0.20.3" "typescript/src")))

The ``treesit-language-source-alist`` variable tells Emacs where it can find a given grammar and what language it is for.
Once defined (and assuming you have the necessary dependencies) you can use ``M-x treesit-install-language-grammar`` command to install one of the grammars you defined.
Alternatively this snippet will install them all in one go

.. code-block:: elisp

   (mapc #'treesit-install-language-grammar (mapcar #'car treesit-language-source-alist))


Major Modes
^^^^^^^^^^^

Switching to tree-sitter powered major modes by default would not be backwards compatible, so if we actually want to make use of the tree-sitter support we need to opt into it.

.. code-block:: elisp
   :project: emacs
   :filename: lisp/alc-treesitter.el

   (if (treesit-language-available-p 'python)
     (add-to-list 'major-mode-remap-alist '(python-mode . python-ts-mode)))


Combobulate
^^^^^^^^^^^

:gh:`mickeynp/combobulate` provides a nice set of movement and editing commands that leverage the parse tree generated by tree sitter.

.. code-block:: elisp
   :project: emacs
   :filename: lisp/alc-treesitter.el

    (use-package combobulate
     :vc (:url "https://github.com/mickeynp/combobulate" :rev "master")
     :hook ((python-ts-mode . combobulate-mode)
            (typescript-ts-mode . combobulate-mode)))