Clojure 将集合指定为每个值中正好有一个

拥有这张地图：

{:id 5
 :fields [{:field :a :val 1}
          {:field :c :val 3}
          {:field :b :val 2}
          {:field :d :val 4}
          ...]}

以及每个字段值的单独规格，如

（s/def:：field-a…

，

（s/def:：field-b…

，

（s/def:：field-c…

---

我应该如何规范它，使映射中的

:fields

包含

{:field a…}

，

{:field b…}

，

{:field c…}

（忽略顺序）和可选的其他值中的每一个（并且正好一个）？

是的，我知道它有点大，但无论如何：

(s/def ::id int?)
(s/def ::val int?)
(s/def ::field keyword?)
(s/def ::some string?)

(s/def ::abstract-field (s/keys :req-un [::field ::val]))

(s/def ::field-a (s/and (s/keys :req-un [::field ::val]) #(= (:field %) :a)))
(s/def ::field-b (s/and (s/keys :req-un [::field ::val]) #(= (:field %) :b)))
(s/def ::field-c (s/and (s/keys :req-un [::field ::val]) #(= (:field %) :c)))
(s/def ::field-d (s/and (s/keys :req-un [::field ::val]) #(= (:field %) :d)))

(s/def ::fields (s/and
                    (s/+ (s/alt :required (s/or :a ::field-a
                                                :b ::field-b
                                                :c ::field-c
                                                :d ::field-d)
                                :rest ::abstract-field))
                    (fn [x] (= [:a :b :c :d]
                               (into [] (sort (map (comp first second) (filter #(= :required (first %)) x))))))))

(let [x1 [{:field :b :val 2}
          {:field :a :val 1}
          ;{:field :a :val 1}
          {:field :d :val 4}
          {:field :e :val 4}
          {:field :c :val 3}
          ]]
    (s/explain ::fields x1)
    (s/conform ::fields x1))

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你的问题很可能是这样回答的：该死，这是一个大规格我希望有一些简洁的解决方案，但我想没有别的办法了。非常感谢你！