A minimal example of attaching a DOM event handler written in Haskell using Webkit

wkhs.cabal

-- Initial wkhs.cabal generated by cabal init.  For further documentation, 
-- see http://haskell.org/cabal/users-guide/

name:                wkhs
version:             0.1.0.0
-- synopsis:            
-- description:         
license:             PublicDomain
license-file:        LICENSE
author:              Dmitry Golubovsky
maintainer:          golubovsky@gmail.com
-- copyright:           
category:            Graphics
build-type:          Simple
-- extra-source-files:  
cabal-version:       >=1.10

executable wkhs
  main-is:             wkhs.hs
  -- other-modules:       
  -- other-extensions:    
  build-depends:       base >=4.8 && <4.9, webkitgtk3, gtk3, transformers, string-quote

  -- hs-source-dirs:      
  default-language:    Haskell2010

wkhs.hs

-- A minimal example of attaching a DOM event handler written in Haskell
-- using Webkit. Based on few other examples if Webkit initialization
-- and loading the initial page. Dependent packages for this program:
-- base >=4.8 && <4.9, webkitgtk3, gtk3, transformers, string-quote

{-# Language QuasiQuotes, ScopedTypeVariables #-}

module Main where

import Data.Maybe
import Data.String.Quote
import Control.Monad.IO.Class

import Graphics.UI.Gtk
import Graphics.UI.Gtk.WebKit.Types
import Graphics.UI.Gtk.WebKit.WebView
import Graphics.UI.Gtk.WebKit.DOM.MouseEvent
import Graphics.UI.Gtk.WebKit.DOM.Document
import Graphics.UI.Gtk.WebKit.DOM.HTMLDocument
import Graphics.UI.Gtk.WebKit.DOM.EventTarget
import Graphics.UI.Gtk.WebKit.DOM.EventTargetClosures

fromMaybeM :: Monad m => String -> Maybe a -> m a
fromMaybeM st = maybe (fail st) return

main = do
  -- initialize Gtk
  _ <- initGUI

  -- create a new window, a scrolled window, and a new webview
  w  <- windowNew
  sw <- scrolledWindowNew Nothing Nothing
  wv <- webViewNew

  -- set the child of the parent to the scrolled window,
  -- and set some others attributes
  set w
    [ containerChild       := sw
    , windowDefaultWidth   := 1000
    , windowDefaultHeight  := 800
    , containerBorderWidth := 0
    ]
  -- set the child of the scrolled windows to the webview.
  set sw [ containerChild := wv ]

  -- load our HTML string on the webview.
  webViewLoadString wv [s|

<div id="abc">
  <h1>Hello (with click handler)</h1>
</div>
<div id="def">
  <h1>Hello (without handler)</h1>
</div>

|] (Just "text/html") ""

  -- on destroying event, we quit the mainloop
  -- onDestroy w mainQuit
  w `on` deleteEvent $ liftIO mainQuit >> return False
  -- show all widgets starting from the root window
  widgetShowAll w

  -- once the page is loaded, install event handlers as needed
  wv `on` documentLoadFinished $ \wf -> do
    doc <- webViewGetDomDocument wv >>= fromMaybeM "no document"
    abc <- getElementById doc "abc" >>= fromMaybeM "no element id=abc found"
    evlstn <- eventListenerNew $ \(e :: MouseEvent) -> do
      x <- getClientX e
      y <- getClientY e
      putStrLn $ "evlist called at (" ++ show x ++ ", " ++ show y ++ ")"
    putStrLn "Installing handler"
    addEventListener abc "click" (Just evlstn) True

  -- start GTK main loop
  mainGUI