type PhoneNumber = String
type Name = String
type PhoneBook = [(Name, PhoneNumber)]

inPhoneBook :: Name -> PhoneNumber -> PhoneBook -> Bool
inPhoneBook name pnumber pbook = (name, pnumber) `elem` pbook

phoneBook =
  [("betty", "555-2938")
  ,("bonnie", "452-2928")
  ,("patsy", "493-2928")
  ,("lucille", "205-2928")
  ,("wendy", "939-8282")
  ,("penny", "853-2492")
  ]

