Hi all, I'm writing a Hardware-oriented DSL deep-embedded in Haskell (similar to Lava, for those familiar with it). One of the goals of the language is to support polymorphic signals (i.e. we would like to allow signals to carry values of any type, including user-defined types) The embedded compiler has different backends: simulation, VHDL, graphical representation in GraphML ... The simulation backend manages to support polymorphic signals by forcing them to be Typeable. In that way, circuit functions, no matter what signals they process, can be transformed to Dynamic and included in the AST for later simulation. The situation is more complicated for the VHDL backend. The Typeable trick works just fine for translating a limited set of predefined types (e.g. tuples) but not for user-defined types, since the embedded-compiler doesn't have access to the user-defined type declarations. One possible solution to access the type-definition of signal values would be constraining them to instances of Data. Then, we could use dataTypeOf to get access to the type representation. (Another option would be using template Haskell's reify, but I would like to avoid that by now) It would certainly be difficult map any Haskell type to VHDL, so, by now we would be content to map enumerate algebraic types (i.e. algebraic types whose all data constructors have arity zero, e.g. data Colors = Green | Blue | Red) So, the question is. Is there a way to figure out the arity of data constructors using Data.Generics ? I'm totally new to generics, but (tell me if I'm wrong) it seems that Constr doesn't hold any information about the data-constructor arguments. Why is it so? Do you think there is a workoaround for this problem? (maybe using some other function from Data.Generics different to dataTypeOf?) Thanks in advance, Alfonso Acosta