I propose a simple program which pops up a window saying 'Hello World' with a button saying 'Bye' which you click and it changes the message to 'Goodbye'. if you click the button again the program exits.
I have been thinkering with the wxWindows library and made a small Haskell binding to it that just supports this example. It was an interesting exercise since the wxWindows library is a large object-oriented C++ library. (but very portable, well supported, efficient and with lots of super widgets, like an openGL canvas and a HTML renderer) Anyhow, I think it comes out rather nicely and I am quite surprised how well the wxWindows library lends itself to Haskell access. -- Daan. ----------------------------------------------------------------- main = wxRun $ do w <- wxCreateFrame wxFRAME_DEFAULT_STYLE wxSetWindowBackgroundColor w white wxSetWindowSize w (Size 100 80) wxSetFrameTitle w "Bye!" l <- wxCreateLabel w "Hello World" wxSetWindowPosition l (Point 10 5) b <- wxCreateButton w "Bye" wxSetWindowPosition b (Point 10 25) wxSetButtonOnCommand b (bye w b l) wxShowWindow w where bye w b l = do wxSetControlLabel l "Goodbye" wxSetButtonOnCommand b (wxWindowClose w False)