clojure - Required keys when destructuring -


is there way have exception raised if keys you're trying destructure aren't in map passed function? use case macro?

for example:

(defn x [{:keys [a b]}] (println b))

i'd work:

(x {:a 1 :b 2})

but raise exception (:b missing)

(x {:a 1})

what pre-condition?

(defn x [{:keys [a b]}]   {:pre [(some? a) (some? b)]}   (println b))  user=> (x {:a 1}) assertionerror assert failed: (some? b)  user/x (no_source_file:1)

edit: yes, use macro handle you. maybe this:

(defmacro defnkeys [name bindings & body]   `(defn ~name [{:keys ~bindings}]      {:pre ~(vec (map #(list 'some? %) bindings))}      ~@body))  (defnkeys foo [a b]   (println b))  (foo {:a 1 :b 2}) (foo {:a 1}) ;; assertionerror assert failed: (some? b) (foo {:a 1 :b nil}) ;; assertionerror assert failed: (some? b)

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