lens-op-ob-hasgotchaix.hs

hasGotchaIx :: IO ()
hasGotchaIx = do
  let bob = User (UserName "bob") 42 Nothing HM.empty
  print "Has bob gold in his inventory?"
  print $ has (inventory . ix "gold") bob
  -- False

  let richBob = User (UserName "bob") 42 Nothing
                  $ HM.fromList [("gold", Item 10 10)]
  print "Has bob gold in his inventory?"
  print $ has (inventory . ix "gold") richBob
  -- True