Clojure:使用多个参数的函数进行过滤

Question

我有一些数据如下

;authors
(def china {:name "China Miéville", :birth-year 1972})
(def octavia {:name "Octavia E. Butler"
              :birth-year 1947
              :death-year 2006})
(def friedman {:name "Daniel Friedman" :birth-year 1944})
(def felleisen {:name "Matthias Felleisen"})

;books
(def cities {:title "The City and the City" :authors #{china}})
(def wild-seed {:title "Wild Seed", :authors #{octavia}})
(def embassytown {:title "Embassytown", :authors #{china}})
(def little-schemer {:title "The Little Schemer"
                     :authors #{friedman, felleisen}})

(def books [cities, wild-seed, embassytown, little-schemer])

所以，如果我想检查给定的书是否有作者，我会使用该函数

(defn has-author? [book author]
  (contains? (:authors book) author)
)

但是我想获取特定作者的书籍，如何通过过滤器获取它？我尝试过:

(defn books-by-author [author books]
 (filter has-author? (books author))
)

Answer 1

更改 books-by-author 中的过滤器，以传递根据 has-author? 定义的谓词以及图书集合，其中每本书都由谓词引用:

(filter #(has-author? % author) books)