hello-gtk2.hs

import Graphics.UI.Gtk

main :: IO ()
main = do
    initGUI
    window <- windowNew
    button <- buttonNew
    set window [ containerBorderWidth := 10
               , containerChild := button ]
    set button [ buttonLabel := "Hello World" ]
    onClicked button $ putStrLn "Hello World"
    onDestroy window mainQuit
    widgetShowAll window
    mainGUI