[plt-scheme] Reading/writing hash-tables

If I write a hash table, like this:

    (write #hash((f . (10))))

Then #hash((f 10)) is written on the current port, but I can't read this 
back in since the reader complains:

    read: expected `.' and value for hash

Is this intended?  Can either the reader or writer be changed so I can 
read and write hash tables?

Thanks,
David