GNU-devel ELPA: r-ts-mode

After installing the package and making sure the R tree-sitter grammar is available, open an .R file and enable r-ts-mode:

(require 'r-ts-mode)
(add-to-list 'auto-mode-alist '("\\.R\\'" . r-ts-mode))

r-ts-mode provides tree-sitter based syntax highlighting, indentation, imenu support, and navigation for R source files.

If the R grammar is not installed yet, you can copy the parser binary from the treesitter.r R package into Emacs’ tree-sitter directory:

(require 'r-ts-mode)
(r-ts-mode-prepare-binaries-from-r-library "R")

Set the variable r-ts-mode-inherit-ess to true and start using treesitter with ESS by calling r-ts-mode from R buffers. It is important to set this variable before r-ts-mode is loaded. With straight you can add it to the :init section. With default Emacs you can use with-eval-after-load. Here is an example:

(with-eval-after-load 'treesit
  (when (treesit-language-available-p 'r)
    (with-eval-after-load 'r-ts-mode
      (setq r-ts-mode-inherit-ess t)
      (push '(ess-r-mode . r-ts-mode) major-mode-remap-alist))))

Roxygen support is provided through r-ts-roxygen-mode. It provides syntax highlighting and CAPF for Roxygen tags.

From version 1.1.3, r-ts-roxygen-mode is not automatically loaded by default. The module is provided as part of the package, but it has to be loaded explicitly.

;; Load Roxygen support after r-ts-mode
(with-eval-after-load
    'r-ts-mode
  (require 'r-ts-roxygen)
  (add-hook 'r-ts-mode-hook #'r-ts-roxygen-mode))

As mentioned in the Dependencies section, there are 3 main known strategies to install the grammars. If you have installed the R package treesitter.r you can use r-ts-mode-prepare-binaries-from-r-library. You need to load the module r-ts-setup first, and then you can call the function interactively (e.g., M-x r-ts-mode-prepare-binaries-from-r-library).

;; Loading r-ts-setup module
(require 'r-ts-setup)

;; Then evaluate the function, or call it interactively
(r-ts-mode-prepare-binaries-from-r-library)

r-ts-mode started following the logic of ESS in which a major mode not only sets the rules for the language, but also defines interaction with the R console, CAPF, xref, linters and more. Soon I came to realize that this is not the right model and decided to change it. At first, everything was kept in ESR, but the code related to tree sitter was segregated into a different module. However, the major mode was still receiving too much responsibility and the name, r-ts-mode was not exactly just a tree sitter major mode for R. Therefore, I took the decision to separate it completely into its own package that specializes Emacs for editing R code, while the rest of the functionality should be delegated to ESR via minor mode(s).

The idea of having it as a separated package was in my head almost since the creation of ESR, mainly because I wanted to have an r-ts-mode that could be easily shared and used without the rest of ESR, something that ESS has never offered. Having it as part of ESR would force the users who only want to benefit from the tree sitter parser, to install a complete package that they might not need. Additionally to that, I received a few comments about trying to make r-ts-mode part of core Emacs, something that cannot be possible as long as it was part of ESR.

R-for-emacs is a new Codeberg Organization to act as a collection of packages and information for the use of R in Emacs. Currently it contains only 3 packages, but the plan is to grow it into a full ecosystem, not only of packages and functionality, but also resources and information specific to the use of R on Emacs.