Hi all. HDirect can generate code as follows: ------------------------------------------------------------ data CONST_DDWAITVBFLAGS = DDWAITVB_BLOCKBEGIN | DDWAITVB_BLOCKBEGINEVENT | DDWAITVB_BLOCKEND instance Prelude.Enum (CONST_DDWAITVBFLAGS) where fromEnum v = case v of DDWAITVB_BLOCKBEGIN -> 1 DDWAITVB_BLOCKBEGINEVENT -> 2 DDWAITVB_BLOCKEND -> 4 toEnum v = case v of 1 -> DDWAITVB_BLOCKBEGIN 2 -> DDWAITVB_BLOCKBEGINEVENT 4 -> DDWAITVB_BLOCKEND _ -> Prelude.error "unmarshallCONST_DDWAITVBFLAGS: illegal enum value " ------------------------------------------------------------ Unfortunately, if you want to interface to a C function which takes a combination of flags added together in a specific argument eg (C): bar ( DDWAITVB_BLOCKBEGIN + DDWAITVB_BLOCKBEGINEVENT ); (Haskell) bar (toEnum (fromEnum DDWAITVB_BLOCKBEGIN) + (fromEnum DDWAITVB_BLOCKBEGINEVENT )) the toEnum function can't deal with the comnbination - it generates a run-time error. Is there a simple way to deal with this situation (the need to associate symbols with specific values, while retaining the ability to lump the values together in a manner reflecting the underlying C semantics)? Should there be another FFI type CEnum? Should the Haskell Enum type be operable with +/&/| or whatever? Merry Christmas Mike Thomas.