main.hs


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{-# LANGUAGE OverloadedStrings #-}

import Graphics.UI.Gtk
import qualified Control.Monad.IO.Class as Cl
import qualified RealCalc

main :: IO ()
main = do _ <- initGUI
          w <- windowNew
          windowSetKeepAbove w True
          set w [ windowDecorated := False, windowTypeHint := WindowTypeHintDock, windowResizable := False ]
          grid <- gridNew
          input <- entryNew
          output <- labelNew (Nothing :: Maybe String)
          gridAttach grid input 0 0 1 1
          gridAttach grid output 0 1 1 1
          containerAdd w grid
          _ <- w `on` deleteEvent $ do
            Cl.liftIO mainQuit
            return False
          _ <- input `on` keyReleaseEvent $ do
            k <- eventKeyName
            let quit = Cl.liftIO mainQuit
            case k of
              "Escape" -> quit
              "Return" -> quit
              _ -> return ()
            s <- Cl.liftIO $ entryGetText input
            case RealCalc.calculate s of
              Nothing -> return ()
              Just r -> Cl.liftIO $ labelSetText output r
            return False
          widgetShowAll w
          mainGUI