Hello, My ycr->swf backend is far enough along that I am ready to figure out how to properly import foreign functions. There are three types of ActionScript 'functions' that I want to import: 1. actionscript primitives, such as ActionSubtract, ActionStringAdd, etc 2. actionscript functions (mostly old functions that predate flash 5.0) 3. actionscript method calls (for flash 5.0 and higher, which has an object system) These each require a slightly different calling convention. So, I think I want to be able to import them by adding lines like this: foreign import primitive "ActionSubtract" actionSubtractInt :: Int -> Int -> Int foreign import ascall "someFunction" someFunction :: Int -> IO Int foreign import asmethod "someMethod" someMethod :: SomeObject -> Int -> IO Int However, to do this requires modifying the yhc frontend to accept these additional calling conventions. In YHC.Core, the calling convention is just a String, so there is no problem representing my new calling conventions in Core. But, the YHC frontend only wants to accept a limited set of predefined calling conventions. Perhaps when the --core flag is present, the frontend should just treat the calling convention as String? Basically, I would extend the Style from: data Style = Ordinary | CCast | Address | FunAddress | Dynamic | Wrapper deriving Eq to: data Style = Ordinary | CCast | Address | FunAddress | Dynamic | Wrapper | Other String deriving Eq And then modify the rest of the code so that when yhc is compiled with the --core flag, the calling convention is not parsed, but simply stuck inside the Other constructor? (Or perhaps, if it parses, the normal constructor is used, but if it fails to parse, then it is just dumped in Other ?) Or, perhaps I am taking completely the wrong approach ? j.