Should the comma operator be removed in D2?

[Ellery Newcomer]

Bill Baxter wrote:
> 
> 
> Note that if comma-as-sequencer was removed, and repurposed as a tuple
> literal  (with "a,b"  making a tuple), and if we specify that tuple
> elements are evaluated in order, then I think this would work as a
> replacement for the current comma operator:
> 
>   (expr1,expr2,expr3)[$-1]
> 
> But the nice thing is you can get the effect of a comma operator that
> evaluates to the value of any expression in the sequence, just using
> different indices.
> Not sure how odious people would find forcing an order of eval on
> tuples, though.

I wouldn't mind.

you'd also have to swap the precedence of assignment and comma, or

	a,b = b,a;

isn't going to do anything useful. But then you can't have

foo(a = b);

unless the entire argument list is a tuple. But then you'd have to
change {something or another} or you can't have nested tuples.

backing up, assuming you don't allow unpareth'd tuples, then what is

( exp )

? Is it a tuple, or a scalar?

I think my personal preference at the moment would be to have tuples of
the form

(, exp , exp ... )
> 
> In the context of a for-loop, you don't care what the value is, so it
> would work as a tuple as-is.  The tuple itself would be the value:
> 
>   for(; i<10; ++i,++j)  // just works

for should be a special case