John Meacham
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.
this should (hopefully) be a short program with most toolkits and demonstrate how one lays out 2 widgets, and responds to user input and mutates the display. note, this is not to compare the toolkits themselves, but the haskell APIs used to access them.
I'd like to see samples using
gtk+hs [..]
This request is quite old by now, but I thought I'll provide you with the Gtk+HS versions of the program nevertheless. I submit two versions: * Bye.hs: Based on the plain Gtk+HS API and IORefs (and naturally very close to the version for gtk2hs). * IHBye.hs: Based on the iHaskell API, which is a higher-level API implemented on top of Gtk+HS and part of the standard Gtk+HS distribution.[1] It's main feature is to avoid IORef's in favour for a more functional abstraction called ports.[2] More information is on the Gtk+HS web page http://www.cse.unsw.edu.au/~chak/haskell/gtk/ The attached code requires the current CVS version of Gtk+HS (to update the button label) and can also be found in the examples directories in CVS. Cheers, Manuel [1] It is not very complete, though. [2] It is unfortunate to have a name clash with Daan's Ports library, but the ports abstraction is being called so already for many years. -- A little demo program that was proposed on gui@haskell.org to compare -- toolkit APIs. This is a version for the plain Gtk+HS API. -- -- There is a single button, which, when clicked once, changes the display -- and, when clicked a second time, terminates the application. -- import Monad import IOExts (IORef, newIORef, readIORef, writeIORef) import Gtk hiding (init, main) import qualified Gtk (init, main) main :: IO () main = do Gtk.init Nothing -- create a new window with a box to pack widgets vertically -- window <- windowNew WindowToplevel vbox <- vBoxNew False 10 window `containerAdd` vbox -- terminate if the window disappears -- window `signalConnect` WidgetDeleteEventHandler (\_ _ -> mainQuit >> return False) -- add the label and button to the box -- label <- labelNew " Hello World " button <- buttonNewWithLabel " Bye " butlbl <- liftM fromWidget $ binGetChild button :: IO Label boxPackStart vbox label True True 2 boxPackStart vbox button True True 2 -- create a stateful signal handler for the button -- clickedAlreadyRef <- newIORef False button `signalConnect` ButtonClickedHandler (\_ -> do clickedAlready <- readIORef clickedAlreadyRef if clickedAlready then mainQuit else do labelSetText label " Goodbye " labelSetText butlbl " Exit " writeIORef clickedAlreadyRef True) -- display the window and enter the event loop -- widgetShowAll window Gtk.main -- A little demo program that was proposed on gui@haskell.org to compare -- toolkit APIs. This is a version for the iHaskell API. -- -- There is a single button, which, when clicked once, changes the display -- and, when clicked a second time, terminates the application. -- import Monad import Gtk (binGetChild) import IH hiding (init, main) import qualified IH (init, main) main :: IO () main = do IH.init Nothing -- create a counter for clicks -- clicksPort <- newPort 0 -- create the label and button, where the button increments the click count -- label <- newLabel " Hello World " button <- newButtonWithLabel " Bye " (clicksPort <-$ (+1)) butlbl <- liftM fromWidget $ binGetChild button :: IO Label -- pack the label and button vertically and embed them into a window -- contents <- newBox Vertical True 10 [widget label, widget button] newWindow " Bye Demo " contents mainQuit False -- clicks are handled by `handleClick' depending on the number of clicks -- let handleClick 2 = mainQuit handleClick 1 = do setLabelText label " Goodbye " setLabelText butlbl " Exit " clicks <- listenToPort clicksPort forkIO $ mapM_ handleClick clicks -- enter the event loop -- IH.main