In a nutshell Data.Typeable is helper module for Data.Data. Data.Typeable provides a "type representation" and Data.Data is a "Generics" library. A "type representation" is set of datatypes that models Haskell's built-in algebraic datatypes. There are simpler type representations than Data.Typeable - Stephanie Weirich's paper describing RepLib might be the most approachable: http://www.seas.upenn.edu/~sweirich/publications.html For documentation on Data.Typeable / Data.Data: http://research.microsoft.com/en-us/um/people/simonpj/papers/hmap/ Data.Data is covered in the first "Scrap Your Boilerplate" paper. Data.Typeable is covered in the second STB paper.