Roman Leshchinskiy
If I'm right then I would suggest not to use copyArray# and copyMutableArray# for GHC < 7.8.
I've grepped today's http://hackage.haskell.org/cgi-bin/hackage-scripts/archive.tar for occurences of those two primitives, and this resulted in the following matches: --8<---------------cut here---------------start------------->8--- ./unordered-containers-0.2.2.1/Data/HashMap/Array.hs: case copyArray# (unArray src) sidx# (unMArray dst) didx# n# s# of ./unordered-containers-0.2.2.1/Data/HashMap/Array.hs: case copyMutableArray# (unMArray src) sidx# (unMArray dst) didx# n# s# of ./persistent-vector-0.1.0.1/src/Data/Vector/Persistent/Array.hs: case copyArray# (unArray src) sidx# (unMArray dst) didx# n# s# of ./persistent-vector-0.1.0.1/src/Data/Vector/Persistent/Array.hs: case copyMutableArray# (unMArray src) sidx# (unMArray dst) didx# n# s# of ./primitive-0.5/Data/Primitive/Array.hs: = primitive_ (copyArray# src# soff# dst# doff# len#) ./primitive-0.5/Data/Primitive/Array.hs: = primitive_ (copyMutableArray# src# soff# dst# doff# len#) ./trifecta-0.53/src/Text/Trifecta/Util/Array.hs: ST $ \ s# -> case copyArray# (unArray src) sidx# (unMArray dst) didx# n# s# of ./trifecta-0.53/src/Text/Trifecta/Util/Array.hs: ST $ \ s# -> case copyMutableArray# (unMArray src) sidx# (unMArray dst) didx# n# s# of --8<---------------cut here---------------end--------------->8--- ...so, are you saying, that those packages above are dangerous to use with GHC<=7.6.1? cheers, hvr