如何处理向量中的每个项目并引用Clojure中的先前值？ [英] How do I operate on every item in a vector AND refer to a previous value in Clojure?

问题描述

给出：

(def my-vec [{:a "foo" :b 10} {:a "bar" :b 13} {:a "baz" :b 7}])

如何迭代每个元素要打印该元素的：a和所有：b的总和到那个点？即：

How could iterate over each element to print that element's :a and the sum of all :b's to that point? That is:

foo 10

bar 23

baz 30

"foo" 10
"bar" 23
"baz" 30

我正在尝试类似的事情，但无济于事：

I'm trying things like this to no avail:

; Does not work!    
(map #(prn (:a %2) %1) (iterate #(+ (:b %2) %1) 0)) my-vec) 

这是行不通的，因为 iterate lazy-seq不能引用my-vec中的当前元素（据我所知）。

This doesn't work because the "iterate" lazy-seq can't refer to the current element in my-vec (as far as I can tell).

TIA！肖恩（Sean）

TIA! Sean

推荐答案

user> (reduce (fn [total {:keys [a b]}]
                  (let [total (+ total b)]
                    (prn a total)
                    total))
              0 my-vec)
"foo" 10
"bar" 23
"baz" 30
30

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