On Thu, 4 May 2023 at 09:53, David Brown via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> On 04/05/2023 10:10, Jonathan Wakely via Std-Proposals wrote:
> >
> >
> > On Thu, 4 May 2023, 08:35 Sebastian Wittmeier via Std-Proposals,
> > <std-proposals_at_[hidden] <mailto:std-proposals_at_[hidden]>>
>
> > wrote:
> >
> > __
> >
> > -----Ursprüngliche Nachricht-----
> > *Von:* Simon Hill via Std-Proposals
> > <std-proposals_at_[hidden]
> > <mailto:std-proposals_at_[hidden]>>
> > *Gesendet:* Mi 03.05.2023 17:21
> > *Betreff:* Re: [std-proposals] New draft proposal: Add "%s"
> > (two-digit truncated-integer seconds) as a std::format
> > conversion specifier for std::chrono time types.
> > *An:* std-proposals_at_[hidden]
> > <mailto:std-proposals_at_[hidden]>;
> > *CC:* Simon Hill <protogrammer_at_[hidden]
> > <mailto:protogrammer_at_[hidden]>>;
> > But people learn that a single logical operator is bitwise, and
> > a double logical operator is boolean. They then have to remember
> > that ^ doesn't have a bitwise equivalent.
> >
> > ^ is already bitwise. You mean ^ has no logical equivalent?
> >
> > Some logical operators use doubled symbols, some not.
> >
> > && and || specifically stand for the short-circuit evaluation.
> >
> > Otherwise for consistency one would want to introduce !! instead of
> > ! for logical NOT, which would lead to a lot of confusion and faulty
> > programs.
> >
> >
> > OK I lied, I do have an opinion on this...
> >
> > ^^ looks like it could be an exponentiation operator to me, and
> > apparently Haskell and D use it for that. And if we added the ability to
> > overload operator^^ then I'm pretty sure people would start abusing it
> > for exponentiation (because there's no operator** in C++).
>
> If anyone wanted to add ^^ to the language for logical xor, it would
> probably be best first to introduce ** for exponentiation, and then
> later ^^ could be added without that confusion.
>
> >
> > If somewhat confusing, terse syntax is preferable to bool(x)^bool(y)
> > then you can already do !x != !y. But I'd just use != for this operation
> > on booleans anyway, not xor (whether in single or double form).
>
> You can also do "!!x ^ !!y", using the "convert to bool operator" !!.
> Alternatively, "!x ^ !y" saves two keypresses :-)
>
> >
> >
> > I think new operators need a much more compelling justification than
> > being a bit less verbose than existing solutions.
> >
>
> I think it would be nice to be able to make your own operators (as you
> can in some languages), using combinations of existing punctuation and
> Unicode characters. People would be able to make vector classes and
> write "a × b" and "a · b", or set classes with "a ∩ b" and "a ∪ b".
> (Library authors would be encouraged to provide alternative text forms,
> in the manner of "bitand".) And in particular, it would mean that
> things like "**" for exponentiation could be added as a library feature
> rather than a language change.
>
> All that's needed are massive changes to the way the language is parsed...
>

Reflection.