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

[Mark Oteiza <mvoteiza@udel.edu>]

Hi,

On 10/07/16 at 04:44am, Kaushal Modi wrote:
> While I have never seen the ¬ character before, I was even more surprised
> that that was set as a notation for 'not'.

You shouldn't be, as it is the 'not' sign!
https://en.wikipedia.org/wiki/Negation

Part of the inspiration for adding more things to some modes has been
that of the p-s-alist in tuareg.el:
https://github.com/ocaml/tuareg/blob/master/tuareg.el#L468

> now all instances of not are replaced with ¬ in lisp-mode if symbol
> prettification is enabled.

By all instances, do you mean there are places other than (not ) that
are getting changed?  Otherwise, that was the point.

> It seems a bit intrusive because I have never seen that notation before.
> While I do know the sqrt notation √, I can imagine this being a source of
> confusion/annoyance for some people.
> 
> Should these notations be instead suggested in the doc-string
> of lisp-prettify-symbols-alist? People interested to see these notations
> can then add that to their personal configs.

Possibly--I added them because I thought they were safe things to add,
being common symbols (fsvo common, it seems).  Safe moreso than and (∧),
or (∨), <=, >=, /= (≠) etc.  In those cases I worry more about
having something like

   (∧ (something so long I want to break the line)
      (foo bar))

and ending up with bad indentation because of prettify-symbols-mode.
Not that anything else is really safe from inducing broken indentation,
it just seems less likely.

In any case, I don't feel strongly about it. One thing I just thought
of is making a mode's foo-prettify-symbols-alist a defcustom--perhaps
that will be nicer.