A Discussion of Tuple Syntax

[bearophile]

Meta:

> Andrei/Walter didn't want to merge that pull request without a 
> full consideration of the different design issues involved, 
> which in retrospect was a good decision.

I agree that before adding some new syntax you have to think well.


> - {a, b} is not as pretty, but it's not that bad of an 
> alternative (though it may still have issues as well)

It has technical issues, they were discussed in one of the last 
threads. Such problems should be added in a note in the DIP32, so 
they don't get lost in time.


> - #(a, b) is unambiguous and would probably be the easiest 
> option. I don't think it looks too bad, but some people might 
> find it ugly and noisy

It looks nice (but I don't know if it's technically usable), I 
have added it at the end of the list of alternative syntaxes:
http://wiki.dlang.org/DIP32#Use_case_of_uniform_tuple_syntax


> I personally think #(a, ?) or #(a, *) would be best, but all 
> that's  really necessary is a symbol that cannot also be an 
> identifier.

I think ? is clear, unambiguous, etc, and I like it. The * is 
already used for pointers, product, dereferencing, ** is used for 
pow, so it's better to not add further meanings to it.


> - Concatenating tuples with ~. This is nice to have, but not 
> particularly important.

In theory I like this operation, but in practice in my D code I 
don't need it often, so I think it should be left out, for later.
In Python I sometimes concatenate tuples, but in such use cases 
they are essentially immutable dynamically typed arrays, losing 
their positional meaning.


Tuples could also be used in switch/case statements, to support a 
very basic form of pattern matching. See also a standard method 
named "unapply" I have discussed a bit here, coming from Scala 
language, that is a very simple solution to solve a significant 
problem:
http://d.puremagic.com/issues/show_bug.cgi?id=596

Bye,
bearophile