I'm not sure how "generally useful" this would be, but I would find it useful to be able to attach notes to core expressions from the Haskell code. The idea being something along the lines of a code annotation like a pragma. For instance, in my Haskell program I would have something like: f x y = case {-# CORE "my first note" #-} g x of ... then, the core would come out with, instead of: case g x of ... we would have case {note "my first note"} g x of ... The reason I would find this useful is somewhat obscure, but the basic idea is that I need to be able to both preprocess code and then change core based on how it was preprocessed. I'd like to send annotations like these out of the preprocessor so they can then be picked up later by my core transformer. If this sounds like a good enough idea to go in, but no one has time to implement it, I could do it myself (probably), but I thought I'd ask the experts first (or if there's anything like this in there currently)... - Hal -- Hal Daume III "Computer science is no more about computers | hdaume@isi.edu than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume