listPhyInterfaces = catMaybes <$> (mapM isPhy =<< sysfsnetOrderedContents)
    where isPhy iface = isPhyInterface iface >>= f where f True = return (Just iface)
                                                         f False = return Nothing                      
listPhyInterfaces = catMaybes <$> (mapM isPhy =<< sysfsnetOrderedContents)
    where isPhy iface = isPhyInterface iface >>= f where f True = return (Just iface)
                                                         f False = return Nothing                      
listPhyInterfaces = catMaybes <$> (mapM isPhy =<< sysfsnetOrderedContents)
    where isPhy iface = isPhyInterface iface >>= f where f True = return (Just iface)
                                                         f False = return Nothing                      