You could potentially also have an interface that defined methods for all the basic types `interface { AsString() (string, error), etc. }` and then each basic t

You could potentially also have an interface that defined methods for all the basic types `interface { AsString() (string, error), etc. }` and then each basic type implements this interface and returns an error if it can't/shouldn't be represented as the requested type. A type-switch could give you the same info you get from the tag and you don't pay for type-assertions