Sure there is. For example the FileReader class documentation[1] has a listing of "All implemented interfaces," and the Readable interface documentation[2] has

Sure there is. For example the FileReader class documentation[1] has a listing of "All implemented interfaces," and the Readable interface documentation[2] has a listing of "All Known Implementing Classes." Pretty much every IDE I know of extends that to include classes from the current package and referenced libraries. So if you need a Readable in Java ("Reader"[3] is an abstract base class, which incidentally lists all of its known subclasses, including FileReader if you follow through InputStreamReader), you have a ready listing available of all the common implementations, which solves this issue straight away, in a way that Go currently lacks. There's nothing stopping Go from having this tooling too (with the caveat that interface cross-references would have to be "All known implemented interfaces" instead of "All implemented interfaces"), it's just not there yet. [1]: http://docs.oracle.com/javase/7/docs/api/java/io/FileReader.html http://docs.oracle.com/javase/7/docs/api/java/io/FileReader.... [2]: http://docs.oracle.com/javase/7/docs/api/java/lang/Readable.html http://docs.oracle.com/javase/7/docs/api/java/lang/Readable.... [3]: http://docs.oracle.com/javase/7/docs/api/java/io/Reader.html http://docs.oracle.com/javase/7/docs/api/java/io/Reader.html