Is it possible to write a wrapper for file handles, that is immutable if we don't plan to swap out the handle and the ref count is in some external data structure and only accessed in ctors/dtors of the struct ? It would look quite a bit like some sort of head immutable, but with no access to the mutable parts.
The motivation is that immutable is inherently shared, so it simplifies code where a file handle might be used by several threads but synchronization is ensured by the operating system or at a higher level in our code. (Otherwise one would have to reimplement read, write, handle, ... with the exact same code, but `shared` attached or cast away `shared`, which is wrong.) -- Marco
