bug#48681: Patch: Make prettify-symbols-mode work with ruby-mode

[Dmitry Gutov]

On 27.05.2021 06:52, William Denton wrote:
> An excellent question, and I think I overstepped things.  The 
> documentation¹ and answers on Stack Exchange² say "&&" and "||" are 
> logical operators (so the logical symbols work) but "and" and "or" have 
> lower precedence and are used differently.

Right. And apparently, it's exactly the same situation in Perl.

> It'd be best to just prettify "&&" and "||" with symbols, and anyone who 
> wants "and" and "or" could add those by hand.  Shall I send a revised 
> patch, or do you just want to delete those bits?

Looking at the various prettify-symbols definitions, there is no great 
consistency.

Even so, we can see that only python-mode uses the symbols ∧ and ∨.

As someone who graduated with an engineering degree a decade ago, the 
"intersection" and "union" symbols look unusual in a programming context 
to me. And a lot of software developers don't have a math background at all.

I'd recommend to just use the list from perl-mode:

  '(("->"  . ?→)
    ("=>"  . ?⇒)
    ("::" . ?∷))

and also add the ("lambda" . ?λ) mapping to it.