Re: prettify-symbols-mode to handle "\alpha-\beta" ...

[Gregory Heytings]

> > > > (defun texinfo-prettify-symbols-compose-p (start end _match)
> > > >    ;; We know the matches all start with a backslash and end with
> > > >    ;; a word-element.
> > > >    (not (or (memq (char-before start) '(?\\))
> > > >             (memq (char-syntax (or (char-after end) ?\s)) '(?w))
> > > >             (nth 8 (syntax-ppss)))))
> > > > (add-hook 'texinfo-mode-hook
> > > >            (lambda ()
> > > >              (push '("\\alpha" . ?α) prettify-symbols-alist)
> > > >              (push '("\\beta" . ?β) prettify-symbols-alist)
> > > >              (setq prettify-symbols-compose-predicate 
> > > > 'texinfo-prettify-symbols-compose-p)
> > > >              (prettify-symbols-mode)))
> > >
> > > That is not completely correct because for "\alpha-\beta", only \beta 
> > > is prettified.
> >
> > No, \alpha-\beta is prettified correctly.  Tested with Emacs 25, 26, 27 
> > and 28.
>
> Have tried it in a texinfo document using
>
> @tex
> $\alpha -\beta \gamma \alpha - \beta \gamma \alpha, \alpha. \alpha- \alpha() 
> \alpha[]$
> @end tex

This works correctly with vanilla Emacs, with the "defun" and "add-hook" 
above.