Idea: void datatype

[pie-flavor]

Right now, there is a gulf between methods that return something, and methods that do not return something. This seems very unlike the rest of C#'s unifiedness, in the same way that it eschewed Java's gulf between objects and primitives. I think it would be a good idea to define void as a type whose only valid value is void, whether this means defining a new zero-sized struct or just using void as an alias to System.ValueTuple with no parameters when used as a type. This would fulfill the same use as Unit in Kotlin, () in Rust, or Void in Java, and allow void methods to be passed where a Func or similar is expected.

[yaakov-h]

See #538, #1279, and #1604.

[ekolis]

I like this idea; it would allow generic types to take void as a type parameter, reducing duplication of code (e.g. Action<int> could be redefined as Func<int, void>).

[pie-flavor]

538 isn't what I'm talking about. never has no instances, void has one instance. The other two talk about some new unit type instead of just treating void as a type from now on.

[eelstork]

I would have uses for a feature in this direction.
I already use an @void single-valued type in places; mainly because void functions do not partake expressions, which breaks flow.
Actual void functions need to be bridged to that, which is not ideal.

Type conversions from void would be handy.

Would be less enthused by an approach equating void to either an empty tuple or null. Let void be void and programmers decide the details of how they wish to handle it.