[Haskell-beginners] FFI foreignPtr construction

[PICCA Frederic-Emmanuel]

Thanks for your help

I end up with this code which I find quite elegant :)

-- data Geometry
data HklGeometry
newtype Geometry = Geometry (ForeignPtr HklGeometry) deriving (Show)

newGeometry :: Factory -> IO Geometry
newGeometry f =
  Geometry <$> (c_hkl_factory_create_new_geometry f >>= newForeignPtr c_hkl_geometry_free)

foreign import ccall unsafe "hkl.h hkl_factory_create_new_geometry"
  c_hkl_factory_create_new_geometry :: Factory -> IO (Ptr HklGeometry)

foreign import ccall unsafe "hkl.h &hkl_geometry_free"
  c_hkl_geometry_free :: FunPtr (Ptr HklGeometry -> IO ())



Cheers

Frederic