Tuple literal syntax

[Walter Bright]

There have been a couple of looong threads about tuples:

http://www.digitalmars.com/d/archives/digitalmars/D/Reddit_why_aren_t_people_using_D_93528.html

http://www.digitalmars.com/d/archives/digitalmars/D/Should_the_comma_operator_be_removed_in_D2_101321.html

A lot of it foundered on what the syntax for tuple literals should be. The top 
of the list is simply enclosing them in ( ). The problem with this is

  (expression)

Is that a parenthesized expression, or a tuple? This really matters, since 
(e)[0] means very different things for the two. Finally, I got to thinking, why 
not just make it a special case:


  ( ) == tuple
  (a) == parenthesized expression
  (a,b) == tuple
  (a,b,c) == tuple
  (a,b,c,d) == tuple

etc.

No ambiguities! Only one special case. I submit this special case is rare, 
because who wants to define a function that returns a tuple of 1? Such will come 
about from generative programming, but:

(a,b,c)[0]

may be how the generative programming works, and that suggests:

(a,0)[0]

as how a user could generate a tuple of 1. Awkward, sure, but like I said, I 
think this would be rare.