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

[pietru]

> Sent: Saturday, February 06, 2021 at 10:45 AM
> From: "Gregory Heytings" <gregory@heytings.org>
> To: pietru@caramail.com
> Cc: emacs-devel@gnu.org
> Subject: Re: prettify-symbols-mode to handle "\alpha-\beta" ...
>
> 
> >>> Would allowing a regexp solve the expression \alpha-\beta, 
> >>> \alpha+\beta, \alpha/\beta, so that \alpha and \beta are prettified 
> >>> seperately?
> >>
> >> That's not necessary.  Just follow Stefan's advice:
> >>
> >> (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)))
> >>
> >> This does what you want.
> >
> > 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