Tuple literal syntax + Tuple assignment

[kenji hara]

2010/10/7 bearophile <bearophileHUGS at lycos.com>:
> Another design decision is if tuples have a nominative or structural type, this problem comes out in this bug report:
> http://d.puremagic.com/issues/show_bug.cgi?id=4128

> Another significant problem is about naming things, currently the situation is a mess:
> http://www.digitalmars.com/d/archives/digitalmars/D/Tuple_TypeTuple_tupleof_etc_113005.html
> http://d.puremagic.com/issues/show_bug.cgi?id=4113
> In the end I have suggested to name "record" the typecons tuples, and "tuple" the typetuples.

On these issues, I'm almost agreed with bearophile

I think we may not use 'Tuple' as 'a structure packed values'.
It is more better that 'Tuple' should *only* use as mixing sequence
types and values.

My proposals are:
1. We should name definitions of structures.
 - "Structure that all of fields have name" shuld be called 'Struct'.
 - "Structure that some of fields have name" shuld be called 'Odd struct'.
 - "Structure that none of fields have name" shuld be called 'Record'.

 Struct∈Odd struct∈Record

2. We remove field namming funcion from std.typecons.tuple, and rename
it to Record.

3. We rename std.typetuple.TypeTuple to Tuple.

--------
pseudo codes:

auto a = Record!(int, int)(10, 20);
auto b = Struct!(int, "x", int, "y")(100, 200);
//a = b; //should not compile, named field(x, y) cannot assign to unnamed field
b = a;   //should compile, unnamed field can assign to named field
assert(b[0] == 10);
assert(b[1] == 20);

auto c = OddStruct!(int, "x", int)(15, 25);
//a = c; //shuld not compile, named field(x) cannot assign to unnamed field
b = c;   //shuld compile
assert(b[0] == 15);
assert(b[1] == 25);
c = a;   //shuld compile
assert(c[0] == 10);
assert(c[1] == 20);

thanks.

Kenji Hara.