To be concrete, suppose the package Foo has an extension Ext which depends on Bar and Baz.
Then it may be nice to let
pkg> add Foo[Ext]
be a shorthand for
pkg> add Foo, Bar, Baz
(thus allowing the fact that Ext depends on Bar and Baz to be an implementation detail).
And further, it may be nice to let
import Foo[Ext]
be a shorthand for
import Foo, Bar, Baz
const Ext = Base.get_extension(Foo, :Ext)