Hi all I am looking at updating HaRe for GHC 7.8.3, and I am fighting my way through the AST changes. One of the things I have had at the back of my mind for a while is to use something like Kure universes or more generally lens to provide a set of isomorphisms from the various flavours of AST into some kind of standardised internal representation, allowing easier tool manipulation. This could potentially decouple the tools from the specific compiler/analyzer, so they could work across GHC 7.6.x, GHC 7.8.x, haskell-src-exts, haste, etc.. Obviously there would be limitations to this where an advance in the language brings in new features, but a lot of useful tool work can be done that does not touch the new stuff. I don't know if anything similar is planned in either ghc-server or another toolchain. My haskell-token-utils is a first limited attempt to bring source code round tripping to a variety of backends, but a more general solution to the AST phase would help tooling in general So, is this worth doing? Is it being done already, or planned? Regards Alan