I am referring to the situations when someone uses 'Ptr a', but the Ptr does not point to anything of type 'a'. If I write 'Ptr Word8', but I am pointing to a Char, then that is not true.
It might not be true, but you might be forced to do such things to use some ugly C library. The Ptr type carries some valuable information, namely: What does my C counterpart expect? It might not be 100% true on the Haskell side, but you are in "unsafe land", anyway, and at some level you *have* to be able to use some white lie when necessary. Note that I'm not saying that this is nice, but I haven't heard of a better alternative yet.