[Haskell-cafe] Combining Wouter's expressions with extensible records

Well, my extension of Wouter's datatypes proved to be unweildy.... So, I'm trying to use http://fmapfixreturn.wordpress.com/2008/05/03/simple-extensible-records-now-... for extensible records. I ran across my first problem rather quickly! data Expr f = In (f (Expr f)) Ok, but to make it part of a record, it needs to implement Data: data Expr f = In (f (Expr f)) deriving Data but this gives No instances for (Data (f (Expr f)), Typeable (Expr f)) arising from the 'deriving' clause of a data type declaration at Planning/Wouter.hs:77:0-42 Any hints? Thanks, -Ron