added check bit setting functionality

src/Hamming/App/Events.hs

@@ -37,6 +37,7 @@ import Graphics.Vty.Input.Events
   )
 import Lens.Micro ((^.), (.~), (%~))
 
+import Hamming
 import Hamming.App.Actions
 import Hamming.App.Types
 
@@ -44,6 +45,8 @@ import Hamming.App.Types
 eventHandler :: Handler
 eventHandler (VtyEvent (EvKey (KChar 'c') [MCtrl])) = halt
 eventHandler (VtyEvent (EvKey (KChar 'q') [])) = halt
+eventHandler (VtyEvent (EvKey (KChar 'c') [])) =
+  modify $ hammingCode %~ setCheckBits
 eventHandler e = gets (^.appMode) >>= \case
   DisplayMode -> displayHandler e
   EditMode _  -> editHandler e