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

[Clément Pit-Claudel]

On 22/05/2020 10.30, Eli Zaretskii wrote:
>> Cc: address@hidden, address@hidden
>> From: Clément Pit-Claudel <address@hidden>
>> Date: Fri, 22 May 2020 09:29:57 -0400
>>
>>> Do font designers really support ligatures from
>>> any arbitrary combination of characters?  If so, where can I read
>>> about this?
>>
>> Yes; that's what I was alluding to in my example with comment signs and 
>> arrows.  I think the pictures on https://github.com/tonsky/FiraCode should 
>> be illuminating.
>>
>> I hope I'm not misunderstanding your question :/
> 
> I was talking about ligatures made from letters, not symbols.

But then how do you handle symbol ligatures?  You showed the example below in 
response to Pip's suggestion of using .+ to support everything that I had 
mentioned; was that only for letters? What about symbols then?

  (set-char-table-range
   composition-function-table '(?f . ?f)
   (list (vector "ffi" 0 'compose-gstring-for-graphic)))