Re: Ligatures (was: Unify the Platforms: Cairo+FreeType+Harfbuzz Everywhere (except TTY))

[Eli Zaretskii]

> Cc: address@hidden, address@hidden, address@hidden
> From: Clément Pit-Claudel <address@hidden>
> Date: Fri, 22 May 2020 15:33:59 -0400
> 
> >> But then how do you handle symbol ligatures?
> > 
> > By using suitable regular expressions.  E.g., you could take the list
> > of ligatures in that FiraCode site and convert them into a regexp or a
> > set of regexps.
> 
> Thanks.  I don't understand why we need to do this

I'm not sure I follow.  Do you understand why
https://github.com/tonsky/FiraCode/wiki/Emacs-instructions includes a
long list of strings to be replaced with ligatures?  If so, why don't
you understand the reason we need to specify similar things when we
use automatic compositions?

And who is "we" in this case?  Users of these features indeed
shouldn't need to mess with these long lists of character sequences,
but why is it a problem if "we" the Emacs developers provide data
bases of such sequences in advance, which user-facing features could
use, hiding them behind much easier UI?

> it seems surprising that we'll need extra Emacs-specific work for each and 
> every font that includes ligatures).

I don't understand how you got to this conclusion.  This is true for
prettify-symbols-mode, but that's exactly why I don't like that
implementation, and why I think automatic compositions are a better
way to go.  And for automatic compositions we didn't yet decide that
any user-level action is needed when you switch to another font, we
are still discussing what is involved.  Up front, I don't yet see why
such font-specific adjustment would be required from users.