books :: Database -> Person -> [Book]
books database person

 =  [ currentBook | (currentPerson, currentBook) <- database , currentPerson == person ]
books :: Database -> Person -> [Book]
books database person

 =  [ currentBook | (currentPerson, currentBook) <- database , currentPerson == person ]
books database person

 =  [ currentBook | (currentPerson, currentBook) <- database , currentPerson == person ]