Named tuple type alias

[ydlv]

C# currently supports tuples with specifically-named properties, like defining:

(double x, double y) point = (1,2); // to access - point.x, point.y

Which is great, by the way. It allows creating simple struct-ish types that you can use, for example, for return types or type arguments.

However, a repetitiveness problem may arise: if your function, say, returns an IReadOnlyCollection<(int id, string result)> (sorry for lack of creativity), and you'll want another function to accept that as a parameter, you need to again write IReadOnlyCollection<(int id, string result)>, which gets more frustrating when names get just a bit longer.

What I'm suggesting is that you'd be able to declare a named-tuple like a named type:

public type Point = (int x, int y);

I've seen a suggestion to do that similar to a using directive, similar to how you can already write something like:

using ShortTypeName = SomeGenericType<TArg1, TArg2>;

But what I'm suggesting is something that will have an access modifier and can be part of a namespace or nested in another type, similar to a delegate declaration. That way you can use it outside of the same CS file, unlike an alias of a using directive.

[canton7]

Sounds a lot like Records. See #3231, #3226, #3213, #3170, #3146, #3137, #2750, #2699, #2691, #1667, and many more besides.

[ufcpp]

see also #423

[YairHalberstadt]

Closing as duplicate between #410, #259, #423