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fancySetExamples :: IO ()
fancySetExamples = do
  let bob = User (UserName "bob") 0 Nothing HM.empty

  -- check out this multi-line string, why don't ya?
  print "Bob changes his name to 'Bill'\
        \, updates his score, and now owns Jeff's pet fish,\
        \who is named Fitzgerald."
  print $
    bob

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overExamples :: IO ()
overExamples = do
  let fitz = Pet (PetName "Fitz")
  let bob = User (UserName "bob") 0 (Just fitz) HM.empty

  print "Bob scores a point. Way to go, Bob."
  -- These all print bob with a score incremented by 1.
  print $ bob & score %~ (\sc -> sc + 1)
  print $ bob & score %~ (+1)
  print $ over score (+1) bob

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-- StorageError in a module somewhere
newtype StorageError = StorageError Text deriving (Eq, Show)

-- WebError wraps storage Error
data WebError
  = WebTextError Text
  | WebStorageError StorageError
  deriving (Eq, Show)

-- Let's convert an 'Either StorageError a' to an 'Either WebError a'

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atIxExamples :: IO ()
atIxExamples = do
  -- Yep, you can use apostrophes in var names. Not that you should...
  let bob'sInventory = HM.fromList [ ("gold", Item 99 10)
                                    , ("silver", Item 10 9)
                                    ]
      bob = User (UserName "bob") 42 Nothing bob'sInventory

  print "Printing Bob's gold value"
  print $ bob ^? inventory . at "gold" . _Just . value

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atIxNonExamples :: IO ()
atIxNonExamples = do
  let bob = User (UserName "bob") 42 Nothing HM.empty
      -- if you were doing this for-real, you would impl and use Data.Default
      defaultGoldItem = Item 0 0

  print "Return the value of Bob's gold, whether he has it or not."
  print $ bob ^. inventory . at "gold" . non defaultGoldItem . value
  -- 0
  print $ bob ^? inventory . at "gold" . _Just . value

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toListOfExamples :: IO ()
toListOfExamples = do
  let tory = HM.fromList [ ("gold", Item 99 10)
                          , ("silver", Item 10 9)
                          ]
      bob = User (UserName "bob") 42 Nothing tory

  print "A list of Bob's items"
  print $ bob ^.. inventory . folded
  -- [Item {_itemValue = 10, _itemWeight = 9},Item {_itemValue = 99, _itemWeight = 10}]

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hasGotcha :: IO ()
hasGotcha = do
  let bob = User (UserName "bob") 42 Nothing HM.empty

  print "Has bob gold in his inventory?"
  print $ has (inventory . at "gold") bob
  -- True

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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?"

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hasn'tExample :: IO ()
hasn'tExample = do
  let bob = User (UserName "bob") 42 Nothing HM.empty
  print "Hasn't bob gold in his inventory?"
  print $ hasn't (inventory . ix "gold") bob
  -- True
  -- As in, "Yes, he doesn't."

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main :: IO ()
main = do
  print "Running 'viewExamples'"
  viewExamples

  print "Running 'composedViewExamples'"
  composedViewExamples

  print "Running 'previewExamples'"
  previewExamples