Hey, Background: I am making a wxhaskell backend for diagrams. Currently I am attempting to implement dashing. The function penSetDashes :: Pen a -> Int -> Ptr c -> IO () takes a bit muster, represented by an array of chars (second parameter is the number of the used bits). The problem is, that the underlying C++ function expects the pointer to be valid even after the function has been executed (until the pen is deleted or another dashing is set). So I am creating a Vector Word8 with the desired bitmuster and I am using Data.Vector.Storable.withUnsafe to pass its internal pointer to penSetDashes. But the pointer must point to something valid even after that! So I was thinking, what if I define data MyPen a = MyPen (Pen a) (Vector Word8) and always keep the vector of dashes with the pen. Will the pointer stay valid? If there are other Ideas on how to this, I am open! Regards, Nathan