You would likely approach it in any style with some helper functions once whatever's in the parentheses or ifs starts feeling big. E.g. in the dot style you could

  fn bookFilter(book: Book) -> bool {
   return book.pageCount > 100 and 
     book.language == "Chinese" and 
     book.subject == "History" and
     book.author.mentions > 10_000
  }
  
  var favoriteFoodsOfFurryPetsOfFamousAuthorsOfLongChineseBooksAboutHistory = books
    .filter(bookFilter)
    .flatMap(book => book.author.pets)
    .filter(pet => pet.is_furry)
    .map(pet => pet.favoriteFood)
    .distinct()