Вывод требуемых элементов из структуры

data Book = Book {
    bookName :: String,
    autor    :: String,
    year     :: Int
} deriving Show
 
book0 = Book{
    bookName = "For Whom the Bell Tolls",
    autor    = "Hemingway E.",
    year     = 1940
}
 
book1 = Book{
    bookName = "To Have and Have Not",
    autor    = "Hemingway E.",
    year     = 1937
}
 
book2 = Book{
    bookName = "On the Road",
    autor    = "Kerouac J.",
    year     = 1957
}
 
book3 = Book{
    bookName = "The Dharma Bums",
    autor    = "Kerouac J.",
    year     = 1958
}
 
book4 = Book{
    bookName = "Catch-22",
    autor    = "Heller J.",
    year     = 1961
}
 
listBooks :: [Book]
listBooks = [book0, book1, book2, book3, book4]
 
--Добавление элемента
add :: [Book] -> Book -> [Book]
add listBooks addBook = listBooks ++ [addBook]
 
--Удаление элемента по индексу
del :: [Book] -> Int -> [Book]
del listBooks index 
 | index < 1 || index > length listBooks = listBooks
 | index == 1 = tail listBooks
 | index == length listBooks = init listBooks
 | otherwise = head listBooks : del (tail listBooks) (index - 1)
 
--Замена элемента по индексу
rep :: [Book] -> Int -> Book -> [Book]
rep listBooks index repBook
 | index < 1 || index > length listBooks = listBooks
 | index == 1 = [repBook] ++ tail listBooks
 | index == length listBooks = init listBooks ++ [repBook]
 | otherwise = take(index - 1)listBooks ++ [repBook] ++ drop(index)listBooks
 
--Поиск книг автора
authorBooks :: String -> [Book] -> [Book]
authorBooks authorName tlist
 | length tlist < 1 = []
 | authorName == autor (head tlist) = [head tlist] ++ authorBooks authorName(tail tlist)
 | otherwise = authorBooks authorName(tail tlist)
 
--Вывод раннего произведения
earliestEdition :: [Book] -> String -> [Book]
earliestEdition authorBooks authorName tlist
 | length authorBooks (authorName tlist) < 1 = []
 | year (head authorBooks(authorName tlist)) < head . tail authorBooks(authorName tlist) = authorBooks authorName(tail tlist)

getEarliest :: [Book]-> String -> [Book]
getEarliest bs a = filter (\b -> (year b)==minYear) al  --  выбираем из книг заданного автора книги, изданные в самый ранний год
                  where al = filter (\b -> (autor b)==a) bs  -- отбираем книги заданного автора
                        minYear = minimum $ map year al -- ищем самый ранний год издания
 
-- Проба:
 
*Main> getEarlier listBooks "Hemingway E."
[Book {bookName = "To Have and Have Not", autor = "Hemingway E.", year = 1937}]
it :: [Book]