Your FP example is needlessly complicated. No one who does FP regularly would write it like that.

  var favoriteFoodsOfFurryPetsOfFamousAuthorsOfLongChineseBooksAboutHistory = books
    .filter(book => 
       book.pageCount > 100 and 
       book.language == "Chinese" and 
       book.subject == "History" and
       book.author.mentions > 10_000
    )
    .flatMap(book => book.author.pets)
    .filter(pet => pet.is_furry)
    .map(pet => pet.favoriteFood)
    .distinct()

Or in Scala:

  val favoriteFoodsOfFurryPetsOfFamousAuthorsOfLongChineseBooksAboutHistory = (for {
    book <- books if
      book.pageCount > 100 &&
      book.language == "Chinese" &&
      book.subject == "History &&
      book.author.metnions > 10_000
    pet <- book.author.pets if
      pet.is_furry
  } yield pet.favoriteFood).distinct

Though, most Scala programmers would prefer higher-order functions over for-comprehensions for this.