Exercises Bookstore collect

Use Case 1: Collecting Books with Descriptions

 library.collect {
    case Book(title, _, _, _, _, Some(description)) => s"$title: $description"
  }

Use Case 2: Calculating Total Value of Books

  library.foldLeft(0.0)((total, book) => total + book.price)

Use Case 3: Finding the Oldest Book

  library.foldLeft(Option.empty[Book]) {
    case (None, book) => Some(book)
    case (Some(oldest), book) if book.year < oldest.year => Some(book)
    case (oldest, _) => oldest
  }

Use Case 4: Grouping Books by Decade

  library.groupBy(book => (book.year / 10) * 10)

Use Case 5: Counting Books by Category

  library.foldLeft(Map.empty[String, Int]) { (counts, book) =>
    counts.updated(book.category, counts.getOrElse(book.category, 0) + 1)
  }