Following up to Keean's message about problems with the RTS interface in ghc-5.04, we have also trouble with that. When compiling C code containing call-ins to Haskell, gcc will complain about RtsAPI.h as follows: /usr/local/lib/ghc-5.04/include/RtsAPI.h:125: syntax error before `const' /usr/local/lib/ghc-5.04/include/RtsAPI.h:126: syntax error before `const' /usr/local/lib/ghc-5.04/include/RtsAPI.h:125: storage size of `GHCziTopHandler_runIO_closure' isn't known /usr/local/lib/ghc-5.04/include/RtsAPI.h:126: storage size of `GHCziTopHandler_runNonIO_closure' isn't known This is gcc 2.95.3 on a Linux (SuSE 7.3 or 7.1 or RH 7.2) box. Commenting out the offending lines in RtsAPI.h seems to work (as in it compiles and runs), but that should not be the proper solution. Is this a bug, or do I need to give gcc some magic options? --C. PS. The same code used to work with ghc-5.02 without complaint.