Unsafe aspects of ByteString

[Iavor Diatchki]

Hello,
I think that your proposal is reasonable.  By the way there is also
another option.  The main point of packCString is to "convert" a
CString to byte string, presumably so that we can use the byte string
operations on it.  An alternative would be to provide the byte string
operations directly on CStrings (perhaps with overloading, perhaps
not).  Then we would not need packCString, and then when working with
ByteStrings we would know that they are safe, but when we work with
CStrings, we would have to watch out, as usual.  Just a thought.
-Iavor