clojure - 如何从具有副作用的函数中获取返回值的集合？

Question

寻找一种从具有副作用的函数生成返回值集合的方法，以便我可以将其提供给 take-while .

(defn function-with-side-effects [n]
  (if (> n 10) false (do (perform-io n) true)))

(defn call-function-with-side-effects []
  (take-while true (? (iterate inc 0) ?)))

更新

这是我在 Jan 回答之后的内容:

(defn function-with-side-effects [n]
  (if (> n 10) false (do (println n) true)))

(defn call-function-with-side-effects []
  (take-while true? (map function-with-side-effects (iterate inc 0))))

(deftest test-function-with-side-effects
  (call-function-with-side-effects))

运行测试不会打印任何内容。使用 doall导致内存不足异常。

Answer 1

不应该是 map解决这个问题？

(defn call-function-with-side-effects []
  (take-while true? (map function-with-side-effects (iterate inc 0))))

如果您希望所有副作用生效，请使用 doall .相关: How to convert lazy sequence to non-lazy in Clojure .

(defn call-function-with-side-effects []
  (doall (take-while true? (map function-with-side-effects (iterate inc 0)))))

请注意我更换了 true在第二行 true? 假设这就是你的意思。