I think, that TypeRep type from Data.Typeable needs Ord class instance. It is unnecessary, but is handy when needed. My use case follows. I try to create graph whose node and arc labels are differently typed. So I can add Int node, Float node and link them by Conversion arc. Right now I am quite good with GADTs that hide values of different types. But when I thinking about querying that structure, I start to want ordered TypeRep. I then can collect different arcs and nodes into different sets and speed up query processing dramatically.