As the extent strings acquire more structure, I'm starting to wonder if encoding the information in strings is the right approach. What's the advantage of putting the information in a string? 1) All Haskell parsers will be able to read any ffi-ified code even if they don't support the language binding the ffi supports. But what does this achieve if the compiler backend doesn't support that ffi? 2) Avoids problems trying to forcefit Java/C/C++/... identifiers/keywords into Haskell and avoid the (ever-growing) set of Haskell keywords. But this could be done by using "" as an escape mechanism whenever there's a conflict. For example, suppose I wanted to foreign import a function called "class" using currently implemented ffi syntax. I just put "" round the offending identifier and I'm done: foreign import "class" clazz :: <whatever> 3) Might be easier to generate good error messages when the language just isn't supported by that compiler. As long as the "language/calling convention" keyword appears near the start of the foreign decl, I think this is easy to do without packing everything into strings. What's the disadvantage of having highly structured strings as part of the ffi spec? There's no big technical issue that I know of but as the strings get more complex (i.e., as we start to write a grammar for them), alarm bells start to go off in my head: o Having a grammar for parsing strings seems to break the classic language structure of: lexical structure context free syntax static semantics dynamic semantics o Reminiscent of C++'s extern "C" declarations. In itself this isn't necessarily bad - but every time I see one of those decls, the word "ugly hack" springs to mind. I suspect that making these strings even more structured would make the hack look worse. o It seems simpler to have just one grammar for Haskell rather than to split it into two separate grammars. By this, I mean, two logically separate grammars (as in the current proposed syntax) instead of two physically separated grammar (as, for example, if someone were to provide a grammar for the C++ ffi binding as appendix G to the report). Is anyone else concerned about this or am I just pissing in the wind? -- Alastair Reid reid@cs.utah.edu http://www.cs.utah.edu/~reid/