It would be useful to have implicit types when creating classes that implement some generics interfaces, as in the following example:

using GLib;
using Gee;

public class AssociativeArray: Object, Map<string,string>
{
        public string get(string key)
        { ... }
}

This could allow to write code like this:

arr = new AssociativeArray();
arr["foo"] = "bar";
stdout.printf("%s\n", arr["foo"]);

The code above generates error at compile-time, expecting explicit inherited types for the get function:

error: Return type and/or parameters of overriding method `AssociativeArray.get' do not match overridden method `Gee.Map.get'.