Re: Your wish list for Ada 202X

["Randy Brukardt" <randy@rrsoftware.com>]

"J Kimball" <spam@example.com> wrote in message 
news:lhvuom$g1$1@loke.gir.dk...
> On 04/07/2014 07:47 PM, Randy Brukardt wrote:
>> "Luke A. Guest" <laguest@archeia.com> wrote in message
>> news:1893909476418340554.191505laguest-archeia.com@nntp.aioe.org...
>>> "Randy Brukardt" <randy@rrsoftware.com> wrote:
>>>> Very early in the design of Ada, there was a proposal to add a unary
>>>> operator symbol specifically for the purpose converting between types.
>>>> Ichbiah and his team rejected the proposal as "+" already exists and 
>>>> has
>>>> no
>>>> other useful purpose. They said that "+" should be used for this 
>>>> purpose.
>>>
>>> I don't get the idea of using plus as a conversion operator, I'd this so 
>>> e
>>> mathematical notation I've not come across?
>>
>> The second part above is so garbled that I can't guess how to respond to 
>> it.
>> The first part is easy, one camp says unary "+" doesn't have a (useful)
>> mathematical meaning, so let's ignore that meaning and use the operator 
>> for
>> conversions. The other camp says that unary "+" has a (useless) 
>> mathematical
>> meaning that should be left alone. Because of the dynamics of the Ada
>> standards process, neither camp ever gets to lead and the net effect is 
>> that
>> we never get *any* conversion operator. Which we've needed from day 1, 
>> IMHO.
>
> Maybe they could agree on a new unused operator being added.

Did you read my original message? That's been suggested for many years. 
There is a camp that thinks "+" is good enough for that, and thus blocks any 
attempts to add another such operator. (There's a lot of people in that 
camp.)

The other group hates the idea of using "+" for that purpose, and blocks any 
use of that as a conversion in the language. (There's a lot of people in 
this group, too -- some are in both groups.)

The ARG operates by consensus. We have no consensus on either point, thus 
nothing gets done at all. (Luckily, this dynamic doesn't happen very often.)

> Of course mathematics
> uses every known graphic in some area. We might be able to agree that an 
> addition should be in the ASCII code points for Unicode which leaves a 
> couple of things that
> stand out that aren't already in use in Ada. "~" seems like a good 
> character with a derivative meaning "approximates" which often all a 
> conversion can do.

If it was up to me, '@' or '#' or '$' or '~' would have been used for this 
long ago.

> UBString := ~String; -- Would drive people from some linguisitic 
> backgrounds crazy, though.

Probably any choice will annoy someone. I think that's the primary argument 
of the "+" backers -- no other solution is really obviously better, so lets 
not clutter the language further. It's hard to argue with that.

                                           Randy.