Translation of the latency function

Trans.purs

pgLatency :: Array Page -> Array Event -> Int
pgLatency pages events =
  snd <<<
    runState
      (for_
        (pagesAndEventsSortedOnTime
        (either
          \p -> whenM ((\s -> fst s && isUsefulPage p) <$> get) (modify_ (snd >>> _ + p.latency))
          \e -> whenM ((\s -> fst s && isUsefulEvent e) <$> get) (modify_ (fst >>> const true)))
        )
      ) ( false /\ 0)
  where
    pagesAndEventsSortedOnTime =
      sortWith
        (_.at ||| _.at)
        ((Left <$> pages) <> (Right <$> events))
    isUsefulPage p =
      fromMaybe false $
        ((elem _ pgUrlList) <$> p.url) <|> ((elem _ pgTitleList) <$> p.title)
    isUsefulEvent e =
      fromMaybe false $
        ((elem _ eTrigger) <$> e.value) <|> ((elem _ pTrigger) <$> e.title)