Working with Erlang for writing RESTful interfaces JSON is the communication "language" of choice. For simplifying the process of JSON to a model the backend could work with efficiently I've created maru_models. This app decodes the JSON with jiffy and uses functions generated by a modified version of Ulf's exprecs to create an Erlang record. The generated functions are created with type information from the record definition and when a property is set for the record through these functions it is first passed to the convert function of maru_model_types to do any necessary processing.
I separated this application into a separate repo to simplify people trying the examples. But the real development will be done in the Maru main repo.