Re: ¬ notation for not? Ref: Add a couple cells to lisp-prettify-symbols-alist

[Ted Zlatanov <tzz@lifelogs.com>]

On Sun, 17 Jul 2016 14:31:26 -0400 Stefan Monnier <monnier@iro.umontreal.ca> wrote: 

>> * how would I add '("not" . ?¬) to the alist?
SM> Depends how we represent the "two alists".

SM> Currently it's

SM>    (push '("not" . ?√) prettify-symbols-alist)

SM> and hopefully we can keep something similar.  This said, the intention
SM> of having two sets is that adding a new element should be unusual: the
SM> extended set should cover most things that someone might like.

What about the distinction between global and local (per mode, per
filename, etc.) prettifications? The UI here is just a programming API,
but it becomes hard for a casual user to override without writing custom
Lisp code, I think?

>> * how would I remove '("sqrt" . ?√) from the alist?

SM> (push ?√ prettify-symbols-inhibited-chars) or customize
SM> prettify-symbols-inhibited-chars.

This is a bit easier than adding, if we assume the inhibition will
always be global. But defcustoms (and the underlying widgets) don't
allow dynamically sourced choices, do they? So the user has to copy and
paste the special symbol?

(I looked in the widget library for dynamic choice lists just this
morning for the gnus-cloud stuff, where it would be nice to offer a
dynamic list of all the possible IMAP server as cloud hosts. I couldn't
find a way. Maybe I missed something.)

Ted