Re: DIP19: Remove comma operator from D and provision better syntactic support for tuples

[Michael]

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;
}