[ESS] trouble with the colored string in R chunk

[Naresh Gurbuxani]

With my default setup, I see character strings rendered in different colour.  Some keywords like “library” and “function” are also shown in different colour.


Sent from my iPhone

> On Feb 2, 2026, at 12:06 PM, LaurentEss via ESS-help <ess-help using r-project.org> wrote:
> 
> Dear Ess-Help list,
> 
> I work with noweb files .Rnw and polymode. I can’t get the string coloring in the R chunks of my files. And yet I searched for a while with the help of chatGPT. Is it possible ? How do we get the string colored in the R chunk ? I succeed to have the string coloring in the .R files but not in the R chunk. When I do M-: major-mode in a R chunk of my .Rnw file I have the answer ess-r-mode but the strings are not colored.
> 
> Thank you very much for your help.
> 
> Laurent
> 
> 
> ----o<--------------------------------------------------------------------------->o-----------------
> 
> Here below is what I put in my init.el file.
> 
> ;; -*- lexical-binding: t; -*-
> ;;
> ;; highlighting R code for ESS in R chunk in .
> ;;
> (with-eval-after-load 'ess-r-mode
> 
>   ;; 🔹 Catégories officielles ESS
>   (setq ess-R-font-lock-keywords
>         '((ess-R-fl-keyword:keywords   . t)
>           (ess-R-fl-keyword:constants  . t)
>           (ess-R-fl-keyword:modifiers  . t)
>           (ess-R-fl-keyword:fun-defs   . t)
>           (ess-R-fl-keyword:assign-ops . t)
>           (ess-R-fl-keyword:%op%       . t)
>           (ess-fl-keyword:fun-calls    . t)
>           (ess-fl-keyword:numbers      . t)
>           (ess-fl-keyword:operators    . t)
>           (ess-fl-keyword:delimiters   . t)
>           (ess-fl-keyword:=            . t)
>           (ess-R-fl-keyword:F&T        . t)))
> 
>   ;; 🔹 Ajouter fonctions R et builtins supplémentaires
>   (setq ess-R-font-lock-keywords
>         (append ess-R-font-lock-keywords
> '(("\\<\\(library\\|require\\|source\\|setwd\\|read\\.csv\\|readRDS\\)\\>"
>                    . font-lock-builtin-face))))
> 
> 
>   ;; 🔹 Coloration des chaînes
>   (font-lock-add-keywords
>    'ess-r-mode
>    '(("\"[^\"]*\"" . font-lock-string-face)
>      ("'[^']*'"   . font-lock-string-face)))
> 
> 
>   ;; 🔹 Ajouter toutes les règles supplémentaires avec font-lock-add-keywords
>   (font-lock-add-keywords
>    'ess-r-mode
>    '(
>      ;; Arguments nommés : x = ...
>      ("\\(\\_<[[:alpha:].]+\\_>\\)[[:space:]]*="
>       1 font-lock-variable-name-face)
> 
>      ;; Pipes : %>% %<>% %$%
>      ("%>%\\|%<>%\\|%\\$%" . font-lock-keyword-face)
> 
>      ;; Fonctions builtins classiques
>  ("\\<\\(library\\|require\\|source\\|return\\|stop\\|warning\\|message\\)\\>"
>       . font-lock-builtin-face)
> 
>      ;; Nombres
>      ("\\<\\([0-9]+\\(\\.[0-9]*\\)?\\)\\>" . font-lock-constant-face)
>      ))
> 
>   ;; 🔹 Pretty symbols pour <- etc.
>   (setq ess-r-prettify-symbols t)
> 
>   ;; 🔹 Outils utiles
>   (add-hook 'ess-r-mode-hook #'outline-minor-mode)
>   (add-hook 'ess-r-mode-hook #'hl-todo-mode))
> 
> 
> ;; Recoloration automatique des chunks R polymode
> (with-eval-after-load 'poly-noweb
>   (add-hook 'poly-noweb+r-mode-hook
>             (lambda ()
>               ;; activer font-lock si ce n'est pas déjà fait
>               (font-lock-mode 1)
>               (font-lock-ensure))))
> 
> 
> 
> ;; Wrapper interactif pour recoloration
> (defun my/ess-r-font-lock-ensure ()
>   "Recolorer le buffer ESS-R courant."
>   (interactive)
>   (font-lock-ensure))
> 
> ;; Raccourci dans tous les chunks R de polymode
> (with-eval-after-load 'poly-noweb
>   (define-key poly-noweb+r-mode-map (kbd "C-c C-l") #'my/ess-r-font-lock-ensure))
> 
> 
> 
> (with-eval-after-load 'poly-noweb
>   ;; Hook pour tous les chunks R à l'ouverture
>   (add-hook 'poly-noweb+r-mode-hook
>             (lambda ()
>               ;; activer font-lock si ce n'est pas déjà fait
>               (font-lock-mode 1)
> 
>               ;; Coloration personnalisée
>               (font-lock-add-keywords
>                nil
>                '(("\"[^\"]*\"" . font-lock-string-face)
>                  ("'[^']*'"   . font-lock-string-face)))
> 
>               ;; Recoloration immédiate
>               (font-lock-ensure)
> 
>               ;; Outline et TODO
>               (outline-minor-mode 1)
>               (hl-todo-mode 1))))
> 
> ;; 🔹 Recolorer tous les chunks R déjà ouverts
> (dolist (buf (buffer-list))
>   (with-current-buffer buf
>     (when (derived-mode-p 'poly-noweb+r-mode)
>       ;; s'assurer que font-lock est actif
>       (font-lock-mode 1)
>       ;; appliquer les couleurs de chaînes
>       (font-lock-add-keywords
>        nil
>        '(("\"[^\"]*\"" . font-lock-string-face)
>          ("'[^']*'"   . font-lock-string-face)))
>       (font-lock-ensure))))
> 
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