Le 27/09/2012 08:17, Jacob Carlborg a écrit :
> On 2012-09-27 00:38, bearophile wrote:
>
>> I have appreciated named fields of D tuples since the beginning, I have
>> found them quite handy. With them sometimes you don't need to unpack a
>> tuple, you can just access its fields with a nice name, avoiding to move
>> around more than one variable.
>
> If you could do something like this:
>
> auto x, y = tuple(1, 2);
>
> Wouldn't that be an acceptable solution instead?
>

It is ambiguous with the comma declaration syntax.

On 2012-09-28 19:09, deadalnix wrote:

> It is ambiguous with the comma declaration syntax.

I could live without it.

-- 
/Jacob Carlborg

On Sunday, 23 September 2012 at 20:39:38 UTC, Andrei Alexandrescu wrote:
> I discussed this with Walter, and we concluded that we could deprecate the comma operator if it helps tuples. So I started with this:
>
> http://www.prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP19
>
> Unfortunately, I started much cockier than I ended. The analysis in there fails to construct a case even half strong that deprecating the comma operator could significantly help tuples. Well it essentially concludes that tuples are mostly fine as they are, and attempts to embellish them syntactically are marred with unexpected problems. Nevertheless, I sure have missed aspects all over, so contributions are appreciated.
>
>
> Thanks,
>
> Andrei

With removed comma operator from D next code will work?

module maybe;

import std.stdio;
import std.algorithm;

R  With(I, R)(I o, R function (I) fun)
{
	return o is null ? null : fun(o);
}

R Return(I, R)(I o, R function (I) fun, R failureResult)
{
	return o is null ? failureResult : fun(o);
}

I If(I)(I o, bool function (I) fun)
{
	return o is null ? null : fun(o) ? o : null;
}

I Unless(I)(I o, bool function (I) fun)
{
	return o is null ? null : fun(o) ? null : o;
}

I Do(I)(I o, void function (I) fun)
{
	return o is null ? null : fun(o), o;
}

void doit(string value)
{
	writeln("Loading... \n");
}


void main()
{
	string name = "D";

	name = name.With((string x) => "Hello, " ~ x ~ "!").
				If((string x) => canFind(x, "D")).
				Do((string x) => x.doit).
				Return((string x) => x ~ " I love You!", "Oh, my!");
	
	writeln(name);
}


especially template function

I Do(I)(I o, void function (I) fun)
{
	return o is null ? null : fun(o), o;
}

On 09/24/2012 11:55 AM, Caligo wrote:
> If tuples are ever introduced, I hope parentheses will not be used.
>
> I would prefer something like this:
>
> tuple<2,1,8>

Not using parentheses: a possibly valid idea!

Using angle brackets: never going to happen.

People HATE angle brackets.  There is extremely good justification for this hatred, because C++ already stepped on that landmine and suffered dearly for it.

If you were to use angle brackets, then I would try to do this:
tuple<a>b,c> d
Which way should this be parsed?
It might be a value tuple of type <bool,bool>
or it might be a declaration: d is of type <bool, typeof(c)>

It is very easy to create cases with angle brackets that are syntactically ambiguous and make it impossible to parse code as a context-free-grammar.  It is harder, but probably possible, to create cases where such a syntax is also completely ambiguous semantically too.

On 09/23/2012 04:40 PM, Andrei Alexandrescu wrote:
> I discussed this with Walter, and we concluded that we could deprecate
> the comma operator if it helps tuples. So I started with this:
>
> http://www.prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP19
>
> Unfortunately, I started much cockier than I ended. The analysis in
> there fails to construct a case even half strong that deprecating the
> comma operator could significantly help tuples. Well it essentially
> concludes that tuples are mostly fine as they are, and attempts to
> embellish them syntactically are marred with unexpected problems.
> Nevertheless, I sure have missed aspects all over, so contributions are
> appreciated.
>
>
> Thanks,
>
> Andrei

Might some of the ambiguity be reduced by defining special tokens for dereferencing tuple elements?

(int[]) a = ([1,2,3]);
assert(a[0]   == 1);
assert(a[[0]] == [1,2,3]);

I suspect that this would allow us to indulge in the attractive notion of single-element tuples.

Would the addition of such a token be considered heresy?