How do I get Emacs to fill sentences, but not paragraphs?

Question

I\'ve seen at least two recommendations on StackOverflow to insert newlines between sentences when editing LaTeX documents. The reason being that the practice facilitates so

Answer 1

Here's what I use, which was mostly cribbed from Luca de Alfaro:

(defun fill-sentence ()
  (interactive)
  (save-excursion
    (or (eq (point) (point-max)) (forward-char))
    (forward-sentence -1)
    (indent-relative t)
    (let ((beg (point))
          (ix (string-match "LaTeX" mode-name)))
      (forward-sentence)
      (if (and ix (equal "LaTeX" (substring mode-name ix)))
          (LaTeX-fill-region-as-paragraph beg (point))
        (fill-region-as-paragraph beg (point))))))

I bind this to M-j with

(global-set-key (kbd "M-j") 'fill-sentence)

The references to "LaTeX" are for AUCTeX support. If you don't use AUCTeX, the let can be simplified to

(let (beg (point))
  (forward-sentence)
  (fill-region-as-paragraph beg (point)))