- new_p = Node.addPri tgt_n inst
- new_s = Node.addSec int_s inst new_pdx
- new_nl = if isNothing(new_p) || isNothing(new_s) then Nothing
- else Just $ Container.add new_pdx (fromJust new_p) $
- Container.addTwo old_pdx int_p
- old_sdx (fromJust new_s) nl
+ new_nl = do -- Maybe monad
+ new_p <- Node.addPri tgt_n inst
+ new_s <- Node.addSec int_s inst new_pdx
+ return $ Container.add new_pdx new_p $
+ Container.addTwo old_pdx int_p old_sdx new_s nl