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On Thursday, 6 January 2022 at 13:18:56 UTC, Timon Gehr wrote:
>BTW, it should work like this:
void foo(string x){} // <- a string, not a tuple
void foo(string x,){} // <- unary tuple
void foo((string,) t){} // <- unary tuple
void foo(string x,int y){} // <- 2-tuple
void foo((string,int) t){} // <- 2-tuple
So perhaps your example would not even work that way; unary tuples shouldn't decay into the underlying type. The concept will need some fleshing out. Maybe it's indeed too hard to actually retrofit this into the language...
Actually I think you were on the right track in your earlier post, with this example:
void foo(int a, string b){} // pattern (int a,string b)
foo(1,"2"); // match tuple (1,"2")
i.e., the argument list itself should be treated like a tuple, and one could also write
auto tup = (1, "2");
foo(tup);
In fact, this is how tuples already work in D, just with nicer syntax--(1, "2") instead of tuple(1, "2").expand.
What the current language can't do, without using wrapper structs like std.typecons.Tuple, is nest tuples. In other words, the question we need to answer is perhaps better framed as "when aren't tuples expanded?"
