This package provides some support for dealing with polytypic data. It lets you escape from the generics world and work with a homogeneous rose tree, which can sometimes be convenient. I realise a more experienced programmer would probably do this differently, but anyhow it was useful to me and I've uploaded it. http://hackage.haskell.org/package/sai-shape-syb There are some examples at http://fremissant.net/shape-syb In particular, it supports GHC staged traversals, so for those trying to work with the GHC AST this might be a helpful tool for filtering, debugging, and suchlike. Kind Regards, Andrew Seniuk rasfar on #haskell