Hi everyone, As we all know, FiniteMap was deprecated, and with GHC-6.6 Data.Map must be used instead. Some function names in Data.Map clash with names in prelude, and Map is usually imported qualified. Happy generates GLR parsers (-l), but the templates it uses keep calling FiniteMap functions. When Data.Map is imported, it's not imported qualified and some function names are ambiguous. I've been using a modified template to generate a GLR parser with GHC-6.6 and it seems to work just fine (there are few changes, not a big deal anyway). I just got the most recent version of Happy and the problem remains, so I applied my changes to GLR_Lib.lhs and ran a diff. The result is attached to this mail. Hope it helps someone else. Cheers, Ivan. PS. I seem to recall having sent this mail months ago. Couldn't find it, though. In case it's been sent twice, I apologise.