"Simon Marlow" <simonmar@microsoft.com> wrote,

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data Point foreign import getMousePos :: Ptr Point -> IO () foreign import getX :: Ptr Point -> IO Int foreign import getY :: Ptr Point -> IO Int

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data Point = Point (Ptr Point) foreign import getMousePos :: Point -> IO ()

I like the second idiom. You are right that there is no need for the application programmer to know whether pointers are involved, because even in the first style, it is not possible to 'peek' inside a Ptr Point to get the `actual' Point value. So why not hide the pointer altogether? Yes.

I presume that should be 'newtype' rather than 'data'?

True. Manuel