boxing.clj

(ns bitwise.reflection-test)

(set! *warn-on-reflection* true)
(set! *unchecked-math* :warn-on-boxed)

(defn foo1 [^String string]
  (reduce + 0
          (map (comp long char) string)))
(defn bar1 [^String string]
  (inc (foo1 string)))

(defn foo2 ^long [^String string] ;; type hint for return value
  (reduce + 0
          (map (comp long char) string)))
(defn bar2 [^String string]
  (inc (foo2 string)))


;; => (bar1 "baz")
;; => Boxed math warning, bitwise/reflection_test.clj:10:3 - call: public static java.lang.Number clojure.lang.Numbers.unchecked_inc(java.lang.Object).

;; => (bar2 "baz") 
;; all good :)