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

[Jonathan M Davis]

On Tuesday, September 25, 2012 13:45:50 Michel Fortin wrote:
> On 2012-09-25 16:38:31 +0000, "Jonathan M Davis" <jmdavisProg at gmx.com> said:
> > On Tuesday, September 25, 2012 12:28:15 Michel Fortin wrote:
> >> Although to make things less confusing, I think the built-in language
> >> tuple should give up its name. It could become a "sequence". Renaming
> >> the built-in one would certainly be less trouble, as code doesn't refer
> >> to it by its name, and you can pick a name that fits better with its
> >> auto-expanding behaviour.
> > 
> > Not referred to by its name? It's refereed to as TypeTuple all over the
> > place. It's arguably a bad name, but it would break a _lot_ of code to
> > change it now.
> TypeTuple is only a construct allowing you to create a built-in
> language tuple, one that does not necessarily match the definition of a
> TypeTuple. The language spec defines a Tuples, TypeTuples, and
> ExpressionTuples with these words (ironically, using the word
> "sequence" twice):
> 
> """
> If the last template parameter in the TemplateParameterList is declared
> as a TemplateTupleParameter, it is a match with any trailing template
> arguments. The sequence of arguments form a Tuple. A Tuple is not a
> type, an expression, or a symbol. It is a sequence of any mix of types,
> expressions or symbols.
> 
> A Tuple whose elements consist entirely of types is called a TypeTuple.
> A Tuple whose elements consist entirely of expressions is called an
> ExpressionTuple.
> """
> Source: http://dlang.org/template.html

I wasn't aware of that being in the language definition, but it doesn't change 
the fact that they're used and referred to in code as TypeTuple, and renaming 
that would break a lot of code. And it _is_ used for the built-in tuple type, 
regardless of whether the spec considers the terms type tuple and expression 
tuple to refer to distinct entities. Rename the stuff in the spec to whatever 
you like, but the library uses the term TypeTuple, so it _is_ used in code.

- Jonathan M Davis