                                        fontify-region-args)))))
 
 (defun haml-highlight-ruby-filter-block (limit)
-  "Highlight a Ruby script expression inside ':ruby' filter block."
+  "If a :ruby filter is found within LIMIT, highlight it."
   (haml-handle-filter "ruby" limit 'haml-fontify-region-as-ruby))
 
 (defun haml-highlight-css-filter-block (limit)
-  "Highlight CSS inside ':css' filter block.
-
-For this to work, 'css-mode.el' must be available, as is automatically
-the case in Emacs 23."
+  "If a :css filter is found within LIMIT, highlight it.
+
+This requires that `css-mode' is available.
+`css-mode' is included with Emacs 23."
   (if (boundp 'css-font-lock-keywords)
       (haml-fontify-filter-region "css" limit css-font-lock-keywords nil nil)))
 
 (defun haml-highlight-js-filter-block (limit)
-  "Highlight Javascript inside ':javascript' filter block.
-
-For this to work, Karl Landström's 'javascript.el' must be available,
-e.g. by installing it from ELPA."
+  "If a :javascript filter is found within LIMIT, highlight it.
+
+This requires that Karl Landström's \"javascript.el\" be available."
   (if (boundp 'js-font-lock-keywords-3)
       (haml-fontify-filter-region "javascript"
                                   limit

                                  nil)))

(defun haml-highlight-textile-filter-block (limit)
  "Highlight Textile inside ':textile' filter block.

Note that the results are not perfect, since textile-mode expects
certain constructs such as 'h1.' to be at the beginning of a line,
and indented haml filter blocks always have leading whitespace.

For this to work, 'textile-mode.el' must be available."
  (if (boundp 'textile-font-lock-keywords)
      (haml-fontify-filter-region "textile" limit textile-font-lock-keywords nil nil)))

(defun haml-highlight-markdown-filter-block (limit)
  "Highlight Markdown inside ':markdown' filter block.

For this to work, 'markdown-mode.el' must be available."
  (if (boundp 'markdown-mode-font-lock-keywords)
      (haml-fontify-filter-region "markdown" limit
                                  markdown-mode-font-lock-keywords

(defconst haml-comment-re "^ *\\(?:-\\#\\|/\\)")

(defun haml-fontify-region (beg end keywords syntax-table syntactic-keywords)
  "Fontify a region between BEG and END using another mode's fontification.

KEYWORDS, SYNTAX-TABLE, and SYNTACTIC-KEYWORDS are the values of that mode's
`font-lock-keywords', `font-lock-syntax-table',
and `font-lock-syntactic-keywords', respectively."
  (save-excursion
    (save-match-data
      (let ((font-lock-keywords keywords)
