: (Show ann, MonadCatch m, Typeable ann) => AnProcess ann -> ProcessPosition -> m (S.Set (S.Set ProcessPosition))
pf proc pos = do proc' <- processAt proc pos
                 res  <- f proc'
                 return $ pos <..> res

fl
pf :: (Show ann, MonadCatch m, Typeable ann) => AnProcess ann -> ProcessPosition -> m (S.Set (S.Set ProcessPosition))
pf proc pos = do proc' <- processAt proc pos
                 res  <- f proc'
                 return $ pos <..> res
pf proc pos = do proc' <- processAt proc pos
                 res  <- f proc'
                 return $ pos <..> res