Add any desired non-function type alias uses to core libraries.

[leafpetersen]

This issue tracks support of the non-function type alias feature. See the enclosing meta-issue for details.

@lrhn anything we want to do here?

cc @franklinyow @lrhn @natebosch @mit-mit

[lrhn]

I'd love typedef any = Object?; in dart:core. Should probably be Any to avoid conflicts, though.

We could defined typedef JsonMap = Map<String, Object?>;, maybe also typedef JsonList = List<Object?>;.

Other than that, I'm not sure there's anything which belongs in the platform libraries.

(Other people have requested capitalized Int and Bool, others have requested lower-case string. Not something I think we should do in the platform libraries).

[lrhn]

Does anybody else have an idea for a typedef that would belong in the core platform libraries (core, async, convert, collection, math or typed_data)?

I'll collect ideas here (no promises to actually add them):

• typedef Any = Object?; in dart:core. (Probably the only "shorthand" we'll allow for a type which is already easy to write).
• typedef JsonMap = Map<String, Object?>; typedef JsonList = List<Object?>; in dart:convert.
• Alternative: typedef JsonMap<T extends Object?> = Map<String, T>;. That will allow you to write JsonMap<JsonMap<JsonList>>. Probably not worth it.
• typedef Int = int; typedef Double = double; typedef Num = num; typedef Bool = bool; in dart:core (for consistency).
• typedef string = String; in dart:core (for a different kind of consistency).
• typedef Nullable<T> = T?; (for people who like C#).

[franklinyow]

Do we know how much work we're doing here?

[leafpetersen]

I think nothing is planned here.

[mit-mit]

@leafpetersen not even typedef JsonMap = Map<String, Object?>; typedef JsonList = List<Object?>; in dart:convert ?

That one seemed obvious. But I could be missing something?

[natebosch]

The JsonMap and JsonList typedefs do add some clarity, I don't feel strongly one way or the other on adding those in dart:convert. I would push back against the other proposals in this thread. If anyone wants to feel like they are writing C# I would prefer that they publish a package with Nullable<T> and whichever capitalizations of the core types make sense to them. @lrhn - do you feel strongly one way or the other on the Json types?

[lrhn]

I personally don't care about JsonX types. I'd like the Any type, but that's the only one I'd use myself.
There has been absolutely no visible interest about any of these types, so I'm fine with doing nothing.