[Haskell-beginners] Haskell way of defining and implementing OO interfaces

4 Jan 2015

      Hi,

I'm writing a password manager that implements a dbus-api using the dbus[1] 
package. I'd like to separate the code that implements from the dbus api from 
the code that stores and retrieves the secrets (passwords). In Java I'd use an 
interface, e.g.:

interface PasswordStore {
  void store(Path path, String secret, Map metadata);
  (String secret, Map metadata) retrieve(Path path);
  (String secret, Map metadata) search(Map criteria);
}

And the dbus-api would export this interface:

dbusClient.export(PasswordStore store)

What would be a Haskell way to do the same? My only idea is to define a record:

data PasswordStore {
    store :: Path -> Secret -> MetaData -> IO ()
  , retrieve :: Path -> IO (Secret, MetaData)
  , search :: Criteria -> IO (Secret, MetaData)
}

Thank you for any suggestions! Thomas Koch

[1] http://hackage.haskell.org/package/dbus-0.10.9