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;; Be careful with `map`, closures, and anonymous functions

(defn typical-closure []
  (let [names (atom [])]
    (fn [arg] (swap! names conj arg) @names)))

;; This works as expected: one function gets created and mapped

(defmacro list-maker [fun args & body]
  `(defn ~fun ~args
     (map (typical-closure) '~body)))

(list-maker foo [x] 1 2 3 4 5)
(foo 100) ; ([1] [1 2] [1 2 3] [1 2 3 4] [1 2 3 4 5])

;; This version recomputes the function for each mappand!

(defmacro list-maker-oops [fun args & body]
  `(defn ~fun ~args
     (map #((typical-closure) %) '~body)))

;; facepalm
(list-maker-oops foo [x] 1 2 3 4 5)
(foo 100) ; ([1] [2] [3] [4] [5])