I have put Release Candidate 3 up at http://www.cse.unsw.edu.au/~chak/haskell/ffi/ Changes wrt to the last version are the following: * 3.2: Clarified the description of foreign types; so far, `IO ()' was strictly speaking not included as a valid return type. * 4.1.5: New section discussing the traps & pitfalls of type promotion with C bindings. * 5.8: Clarified documentation for `MarshalAlloc.free'. * 5.8: Added `MarshalAlloc.realloc'. Moreover, I would like to draw your attention to the following points, which we should solve before I post the next version to `haskell@haskell.org': * Olaf Chitil has pointed out some unclear points wrt to () and IO () as a result type in foreign declarations in the previous version of the Addendum. I have edited Section 3.2 to improve this, but you may want to check out that the new version meets your expectations. * I have added Section 4.1.5 as a consequence of the recent discussion on argument type promotion on this list. It seemed that everybody agreed what the FFI should do, but that a detailed explanation in the specification is needed, so I have added one. Please check whether you find it sufficient. * I think, for reasons of orthogonality `MarshalAlloc' should include realloc :: Storable b => Ptr a -> IO (Ptr b) I have added this in the document. Let me know if anybody disagrees with this. * There is the open question, raised by SPJ, of whether we like to have something like import_entity -> [String] export_entity -> [String] See my message from yesterday. * Sigbjorn, while adding support for OS threads to GHC, has introduced a new safety mode `threadsafe'. It seems worthwhile to include this into the Addendum. On systems that don't support OS threads, `threadsafe' might behave like `safe', but at least code that uses `threadsafe' would still be valid on other systems. The semantics is as follows: unsafe must not call back safe may call back; if it blocks outside Haskell, the whole Haskell system blocks threadsafe on systems supporting OS threads, the Haskell runtime will not block, even if the call blocks; must call an OS-thread safe procedure ('safe' remains the default.) If there are no objections, I will add the latter two changes to the FFI Addendum. Cheers, Manuel