Clojure 字符串索引超出范围:-1

Question

我正在尝试将一个 clojure 映射转换为 Mathematica 图，映射关系是

{:60 [:34], :14 [:13], :39 [], :37 [:21], :59 [], :27 [:26 :32], :42 [], :45 [], :31 [:28], :40 [], :18 [:19], :52 [], :12 [:11], :11 [:9 :12 :17 :16], :24 [:25], :10 [:9], :21 [:16 :37 :36], :56 [], :23 [:25], :13 [:14], :0 [:1], :58 [], :30 [:29], :38 [], :53 [], :4 [:2 :5 :54], :43 [], :57 [], :26 [:28], :16 [:11 :5 :21 :34], :44 [], :7 [:8 :9], :35 [], :55 [], :1 [:0], :50 [], :8 [:7], :36 [:21], :22 [], :47 [], :25 [:24], :9 [:7 :10 :11], :20 [:19], :17 [:11], :46 [], :32 [:33 :35 :34], :49 [], :28 [], :48 [], :19 [:18 :20], :2 [:3 :4], :5 [:4 :6 :16 :15], :41 [], :15 [:5], :3 [], :6 [:5], :33 [], :51 [], :54 [], :29 [:30], :34 []}

函数定义为

 (defn relations-export []
  (do
    (def temp "{")
    (for [x relations]
      (map (fn [l] (def temp (str temp (clojure.string/replace (str (first x) " -> " l ", ") ":" "")))) (second x)))
    (def temp (str (subs temp 0 (- (count temp) 2)) "}" ))
    )
  )

它应该给出一个字符串，例如

"{60 -> 34, 14 -> 13, 37 -> 21, 27 -> 26, 27 -> 32, 31 -> 28, 18 -> 19, 12 -> 11, 11 -> 9, 11 -> 12, 11 -> 17, 11 -> 16, 24 -> 25, 10 -> 9, 21 -> 16, 21 -> 37, 21 -> 36, 23 -> 25, 13 -> 14, 0 -> 1, 30 -> 29, 4 -> 2, 4 -> 5, 4 -> 54, 26 -> 28, 16 -> 11, 16 -> 5, 16 -> 21, 16 -> 34, 7 -> 8, 7 -> 9, 1 -> 0, 8 -> 7, 36 -> 21, 25 -> 24, 9 -> 7, 9 -> 10, 9 -> 11, 20 -> 19, 17 -> 11, 32 -> 33, 32 -> 35, 32 -> 34, 19 -> 18, 19 -> 20, 2 -> 3, 2 -> 4, 5 -> 4, 5 -> 6, 5 -> 16, 5 -> 15, 15 -> 5, 6 -> 5, 29 -> 30}"

但它作为 CompilerException java.lang.StringIndexOutOfBoundsException： 字符串索引超出范围： -1， 编译：(form-init2059367294355507639.clj：269：20(

问题是我逐行测试了(do &expr(中的代码，它们按预期工作，但是当我将它们放入此函数时，我遇到了错误。

Answer 1

你似乎缺少一些Clojure的基础知识，因为你使用的是def-in-def。这是你应该开始的地方。

将问题拆分为较小的问题而不是直接将它们放在一起可能是个好主意。因此，第一步是创建组合，然后将它们转换为所需的字符串组合，并在最后一步中创建完整的字符串。这可能看起来像这样：

(require '[clojure.string])
(defn relations-export [data]
  (let [combinations (for [[k vs] data, v vs] [k v])
        comb-strings (map (fn [[k v]] (str (name k) " -> " (name v))) combinations)]
    (str "{" (clojure.string/join ", " comb-strings) "}")))

(评论中的应用建议，感谢@Thumbnail(

请尝试Clojure基础知识，以真正开始使用该语言。一个好的起点肯定是 braveclojure.com