Adding Unicode operators to D

[Andrei Alexandrescu]

Bruno Medeiros wrote:
> Andrei Alexandrescu wrote:
>> Spacen Jasset wrote:
>>> Bill Baxter wrote:
>>>> On Thu, Oct 23, 2008 at 7:27 AM, Andrei Alexandrescu
>>>> <SeeWebsiteForEmail at erdani.org> wrote:
>>>>> Please vote up before the haters take it down, and discuss:
>>>>>
>>>>> http://www.reddit.com/r/programming/comments/78rjk/allowing_unicode_operators_in_d_similarly_to/ 
>>>>>
>>>>>
>>>>
>>>> (My comment cross posted here from reddit)
>>>>
>>>> I think the right way to do it is not to make everything Unicode. All
>>>> the pressure on the existing symbols would be dramatically relieved by
>>>> the addition of just a handful of new symbols.
>>>>
>>>> The truth is keyboards aren't very good for inputting Unicode. That
>>>> isn't likely to change. Yes they've dealt with the problem in Asian
>>>> languages by using IMEs but in my opinion IMEs are horrible to use.
>>>>
>>>> Some people seem to argue it's a waste to go to Unicode only for a few
>>>> symbols. If you're going to go Unicode, you should go whole hog. I'd
>>>> argue the exact opposite. If you're going to go Unicode, it should be
>>>> done in moderation. Use as little Unicode as necessary and no more.
>>>>
>>>> As for how to input unicode -- Microsoft Word solved that problem ages
>>>> ago, assuming we're talking about small numbers of special characters.
>>>> It's called AutoCorrect. You just register your unicode symbol as a
>>>> misspelling for "(X)" or something unique like that and then every
>>>> time you type "(X)" a funky unicode character instantly replaces those
>>>> chars.
>>>>
>>>> Yeh, not many editors support such a feature. But it's very easy to
>>>> implement. And with that one generic mechanism, your editor is ready
>>>> to support input of Unicode chars in any language just by adding the
>>>> right definitions.
>>>>
>>>> --bb
>>> I am not entirely sure that 30 or (x amount) of new operators would 
>>> be a good thing anyway. How hard is it to say m3 = 
>>> m1.crossProduct(m2) ? vs m3 = m1 X m2 ? and how often will that 
>>> happen? It's also going to make the language more difficult to learn 
>>> and understand.
>>
>> I have noticed that in pretty much all scientific code, the f(a, b) 
>> and a.f(b) notations fall off a readability cliff when the number of 
>> operators grows only to a handful. Lured by simple examples like 
>> yours, people don't see that as a problem until they actually have to 
>> read or write such code. Adding temporaries and such is not that great 
>> because it further takes the algorithm away from its mathematical form 
>> just for serving a notation that was the problem in the first place.
>>
> 
> But what operators would be added? Some mathematician programmers might 
> want vector and matrix operators, others set operators, others still 
> derivation/integration operators, and so on. Where would we stop?
> I don't deny it might be useful for them, but it does seem like too 
> specific a need to integrate in the language.

I was thinking of allowing a general way of defining one Unicode 
character to stand in as one operator, and then have libraries implement 
  the actual operators.

There's the remaining problem of different libraries defining the same 
character to mean different operators. This may not be huge as math 
subdomains tend to be rather consistent in their use of operators. 
Across math subdomains, types and overloading can take care of things.

Also, ascii representation should be allowed for operators, and one nice 
thing about Unicode characters is that many have HTML ascii and 
human-readable names, see 
http://www.fileformat.info/format/w3c/htmlentity.htm. So 
\unicodecharname may be a good alternate way to enter these operators. 
For example, the empty set could be \empty, and the cross-product could 
be written as \times. So

c = a \times b;

doesn't quite look bad to me.

One nice thing about this is that we don't need to pore over naming and 
such, we just use stuff that others (creators and users alike) have 
already pored over. Saves on documentation writing too :o).


Andrei