clojure入门（4）

(sort-by :a [{:a 3} {:a 2} {:a 4}])
;=> ({:a 2} {:a 3} {:a 4})

(sort-by (comp - :a) [{:a 3} {:a 2} {:a 4}])
;=> ({:a 4} {:a 3} {:a 2})

(sort #(- (:a %1) (:a %2)) [{:a 3} {:a 2} {:a 4}])
;=> ({:a 2} {:a 3} {:a 4})

comp
partial
complement
fnil

frequencies
group-by
partition-by
flatten