[cap-talk] Abstractions that subsume capabilities

[Kevin Reid]

On Mar 12, 2008, at 10:28, Sandro Magi wrote:

> The suggestions made thus far were to close this hole. I think  
> Haskell's
> mistake here is the I/O signatures and main's in particular: IO ().
>
> At a coarse granularity, they should be:
>
> main		:: World -> IO ()
> openFile        :: World -> FilePath -> IOMode -> IO Handle

To demonstrate how this change is sufficient to permit capability  
structure:

   -- ignoring the need to prohibit ".." etc. for simplicity.
   openRestricted world prefix path = openFile world (prefix ++ path)

   main world = do
     ...
     h <- untrusted (openRestricted world "/sandbox/")
     ...

Of course, one would want to have libraries providing utilities like  
openRestricted.

-- 
Kevin Reid                            <http://homepage.mac.com/kpreid/>