Re: [Haskell-cafe] automatically deriving Map and Filter on datatypes etc.

Hi

PS Why isn't Functor derivable?

Derive can do it: http://www.cs.york.ac.uk/~ndm/derive I believe that Twan (the author of Functor deriving in Derive) is trying to get this suggested for Haskell' as a proper deriving. As for the original question, Uniplate will certainly do map, and will probably help with filter - as the definition of Filter is not obvious given the type. And you can have automatic deriving with Uniplate (see PlateData in the paper or the module structure) http://www.cs.york.ac.uk/~ndm/uniplate Thanks Neil