I am using boost spirit 1.39. On gcc the compilation times are acceptable. However on AIX with v10.1 compiler, it fails to even compile. After 24hrs waiting, I gave up. Ok I realise that the grammer needs to split. Is there any _small_ examples out there, that demonstrates this technique for a beginner ? In my case I have one grammer and ~70 rules. Take the following rule: rule<ScannerT, string_closure::context_t> identifier ; identifier = lexeme_d [ (alnum_p || ch_p('_')) >> *(alnum_p || ch_p('_')) ] [ identifier.name = construct_<std::string>(arg1, arg2) ] ; What is the technique for converting it into a grammer, that is separately compiled ? Also how would I reference it again, without including the header file, from another rule dotPath = ( str_p(".") >> +( str_p("/") >> identifier ) ) [ dotPath.name = construct_<std::string>(arg1, arg2) ] ; Any help would greatly appreciated. Best regards, Ta, Avi