Nullable types are not assinable to a variable.

[Reductions]

At the moment this is not posible:

void main() {
  Type t = int?; // I also tried to do: Type t = (int?);
  print(t);
}

Here is the error I get:

test_dart.dart:2:16: Error: Expected an identifier, but got ';'.
Try inserting an identifier before ';'.
  Type t = int?;
               ^
test_dart.dart:2:16: Error: Expected ':' before this.
  Type t = int?;
               ^
test_dart.dart:2:12: Error: A value of type 'Type' can't be assigned to a variable of type 'bool'.
 - 'Type' is from 'dart:core'.
  Type t = int?;
           ^

[eernstg]

Use this:

Type typeOf<X>() => X;

void main() {
  Type t = typeOf<int?>();
  print(t);
}

Cf. #123, I'll close this as a duplicate.

[Levi-Lesches]

Would the new typedefs help with this?

typedef MaybeInt = int?

void main() {
  Type t = MaybeInt;
  print(t);
}

[Reductions]

@Levi-Lesches You can not typedef anything but functional types.

[Levi-Lesches]

That's being changed in #65, and hopefully releasing soon. Hopefully that should fix this pattern.

[eernstg]

It is indeed possible to use the new and more general kind of type alias (currently needing --enable-experiment=nonfunction-type-aliases, soon to be enabled by default):

typedef MaybeInt = int?;

However, I'd still recommend using something like typeOf<int?>() when possible, because the type alias adds MaybeInt to the global namespace, and that would typically not be helpful.

[Reductions]

Glad to hear that typedef of nonfunctional types is coming to dart. It will be beneficial when working with nested maps and lists.
@eernstg

[eernstg]

Thanks, @Reductions!

I'll close this issue: It may be seen as a proposal to allow T? as an expression when T is a type, but that's already on the agenda in #123 (comment), hence the 'state-duplicate' label.