Yeah, however it's spelled this is something I would love to see come to the language officially without the need for arcane workarounds like @xwu's. For better or worse I think the existence of @_implements has acted as a bit of a pressure release valve for the urgency of solving this, but the fact that there's an existing unofficial feature for this should hopefully make the implementation path easier for any community member who wants to pick this up!
If only we had such a thing. 
I suppose since this would be a new syntactic construction we could require that the name here always be fully-qualified to resolve the 'type with the same name as the module' issue, but it might be surprising that the lookup rules here are not the same as elsewhere.