The following TODOs should be addressed. Should you have the inclination to address them, please feel free to send pull requests!
Currently there are only Unit tests in testsuite/tests/Text/RDF/RDF4H/ for the XmlParser and TurtleParser instances. Automated QuickCheck tests would add confidence in the stability in this library.
There are no tests for the NTriplesParser instance.
Examples help newcomers to the library understand it should be used. Adding plenty of simple examples could be added to the examples/ directory.
The RDF typeclass is very simple. More interesting graph manipulation and querying is left currently to the user. A more exotic API could be inspired by the [Jena](http://jena.apache.org/documentation/javadoc/jena/) library.
The haddock documentation is not very helpful. It would be good to add a verbose description of the RDF standard and a couple of simple coding examples in the src/Data/RDF.hs file.