(% program-state +-
    ...
)

(@ +-
    (# msg-in (@ msg +-
                  (# process state msg (@ st +-
                                           (st .state)
                                       )
                  )
    -
        (% 
            .state ..
        )
    )
)

(@ process state st @fp +-
    ...
+
    {program-state} state
)
