Shall we generate converters for structural types

[Atry]

Suppose we have a type defined in TypeScript like this:

@js.native
trait MyType extends StObject {
  val field: Double = js.native
}

The idea is to also generate the following helper:

object MyType {
  @inline implicit def isStructural = <:<.refl[MyType].asInstanceOf[js.Any { val field: Double } =:= MyType]
}

With the help of the =:= instance, other JS types that contain a field: Double can be converted to MyType safely.

[oyvindberg]

Haha wow! that's rather interesting!

I honestly have no idea. I've been avoiding structural types throughout my adventures through Scala.

How useful will this be? is there a subtype relationship between structural types where one is a subset of the other? would this be transitive between types?

Do you know how and if Selectable in Scala 3 would apply here?

[Atry]

How useful will this be? is there a subtype relationship between structural types where one is a subset of the other?

<:< and =:= are type classes in the Scala library to prove sub-typing, but they are not actually sub-typing from the compiler's point of view. So it only helps the user to convert between types safely, instead of affecting the compiler behavior.

would this be transitive between types?

It would require the user to call <:<.compose manually to create transitive instances.