IO ()
From Haskell, I want to call a C function that returns a struct by value (rather than, say, returning a pointer). For example: typedef struct { double x; double y; } point_t; point_t polar(double theta); I can create a Haskell type Point and make it an instance of Storable easily enough: data Point = Point CDouble CDouble instance Storable Point where -- insert obvious code here And now I want to do something like this: foreign import ccall unsafe polar :: CDouble -> IO Point ...but that doesn't appear to be legal (at least in GHC 6.12). Is there any way to import this C function into Haskell _without_ having any additional wrapper C code? I mean, I suppose I could write something like: // C: void polar_wrapper(double theta, point_t* output) { *output = polar(theta); } -- Haskell: foreign import ccall unsafe polar_wrapper :: CDouble -> Ptr Point - polar :: CDouble -> IO Point polar theta = do -- insert obvious code here ...but that's a lot of extra boilerplate if I have many such functions to wrap, and it seems like GHC should be able to do that sort of thing for me. P-: Cheers, -Matt