All, Just to let people know, we've progressed somewhat on the precompiled headers front. Outwardly, the patch is much like Axel described previously. Internally, we rewrote the serialisation using the Binary module from GHC. This allowed us to use shared strings which reduces the file size considerably (~20Mb to ~9Mb). It still uses a lazy reading scheme so while producing the *.precomp file is still rather slow but reading it is really quick. For some reason (as yet undiscovered) the serialisation is very slow and memory hungry. On my machine it takes 16 seconds to parse all of gtk/gtk but 45 seconds to serialise all that to disk. Our current branch is hosted in the gtk2hs cvs: http://cvs.sourceforge.net/viewcvs.py/gtk2hs/gtk2hs/tools/c2hs/ It is based on c2hs 0.13.4. There are one or two interesting patches in addition to the precompiled headers patch: http://cvs.sourceforge.net/viewcvs.py/gtk2hs/gtk2hs/tools/c2hs/gen/GenBind.hs?r1=1.1&r2=1.2 This one makes c2hs chase typedef'ed types so that C function prototypes that use typedef'ed types get propper Haskell types rather than Ptr (). http://cvs.sourceforge.net/viewcvs.py/gtk2hs/gtk2hs/tools/c2hs/chs/CHS.hs?r1=1.1&r2=1.2 This one makes c2hs understand hierarchical module names. Duncan