Intercept link clicks in PureScript

LinkCapture.purs

import Prelude
import Control.Monad.Maybe.Trans (MaybeT(..), runMaybeT)
import Control.Monad.Trans.Class (lift)
import Data.Maybe (Maybe(..), maybe)
import Data.Maybe as Maybe
import Data.Newtype (wrap)
import Data.String as String
import Effect (Effect)
import Web.DOM.Node (Node)
import Web.DOM.Node as Node
import Web.Event.Event (Event)
import Web.Event.Event as Event
import Web.Event.EventTarget as EventTarget
import Web.HTML as HTML
import Web.HTML.HTMLDocument as HTMLDocument
import Web.HTML.HTMLLinkElement (HTMLLinkElement)
import Web.HTML.HTMLLinkElement as HTMLLinkElement
import Web.HTML.Window as Window

captureLinkClicks :: forall msg. (String -> Effect msg) -> Effect Unit
captureLinkClicks onLinkClicked = do
  document <- HTML.window >>= Window.document
  listener <- EventTarget.eventListener $ clickListener onLinkClicked >>> runMaybeT
  EventTarget.addEventListener (wrap "click") listener true (HTMLDocument.toEventTarget document)

clickListener :: forall msg. (String -> Effect msg) -> Event -> MaybeT Effect Unit
clickListener onLinkClicked event = do
  eventNode <- MaybeT <<< pure $ Event.target event >>= Node.fromEventTarget
  linkElement <- MaybeT $ findLink eventNode
  href <- lift $ HTMLLinkElement.href linkElement
  crossOrigin <- lift $ isCrossOrigin linkElement
  if crossOrigin == false then
    lift
      $ do
          _ <- Event.preventDefault event
          _ <- onLinkClicked href
          pure unit
  else
    pure unit

findLink :: Node -> Effect (Maybe HTMLLinkElement)
findLink node = case HTMLDocument.fromNode node of
  Just _ -> pure Nothing
  Nothing -> case HTMLLinkElement.fromNode node of
    Just linkElement -> pure $ Just linkElement
    Nothing -> Node.parentNode node >>= maybe (pure Nothing) findLink

isCrossOrigin :: HTMLLinkElement -> Effect Boolean
isCrossOrigin = HTMLLinkElement.href >>> map (String.indexOf (wrap "://")) >>> map Maybe.isJust