Trees that go into macro annotation arguments are purposefully untyped. However running c.typeCheck(q”(??? : <tree that represents the parent>)”).tpe will provide the missing information. Don’t forget to duplicate that tree before typechecking, because c.typeCheck mutates the tree in place, which might be undesireable. In case when both parent and child are declared in the same … Read more
I don’t think there’s anything deeper going on than what you have originally said: it’s just syntactic sugar whereby the compiler converts f(a) into f.apply(a) as a special syntax case. This might seem like a specific rule, but only a few of these (for example, with update) allows for DSL-like constructs and libraries.
The companion object basically provides a place where one can put “static-like” methods. Furthermore, a companion object, or companion module, has full access to the class members, including private ones. Companion objects are great for encapsulating things like factory methods. Instead of having to have, for example, Foo and FooFactory everywhere, you can have a … Read more