Hi, Upgrading from GHC 6.6 to 6.8 has caused some code to stop working: ---------------------------------------------------------------------- {-# OPTIONS_GHC -fglasgow-exts #-} module Data2 where data CCompany data Paradise :: * -> * where CC :: Paradise CCompany rewrapCC CC = [] ---------------------------------------------------------------------- [1 of 1] Compiling Data2 ( Data2.hs, interpreted ) Data2.hs:12:9: GADT pattern match in non-rigid context for `CC' Tell GHC HQ if you'd like this to unify the context In the pattern: CC In the definition of `rewrapCC': rewrapCC CC = [] This code is from the Uniplate benchmarking code, which runs the Paradise benchmark from SYB on Uniplate, Compos and SYB. The Compos code uses GADT's, so the program first needs to convert from standard data structures to GADT's before it can work, then back at the end. It's the problem of converting from a GADT to a normal data structure that is failing. So is there an easy workaround? Or should I be asking GHC HQ to unify things? Thanks Neil