The following code appears to force line-seq to read 4 lines from file. Is this some kind of buffering mechanism? Do I need to use lazy-cat here? If so, how can I apply a macro to a sequence as if it were variadic arguments?
(defn char-seq [rdr]
(let [coll (line-seq rdr)]
(apply concat (map (fn [x] (println \,) x) coll))))
(def tmp (char-seq (clojure.contrib.io/reader file)))
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#'user/tmp
Part of what you're seeing is due to apply, since it will need to realize as many args as needed by the function definition. E.g.:
user=> (defn foo [& args] nil) #'user/foo user=> (def bar (apply foo (iterate #(let [i (inc %)] (println i) i) 0))) 1 #'user/bar user=> (defn foo [x & args] nil) #'user/foo user=> (def bar (apply foo (iterate #(let [i (inc %)] (println i) i) 0))) 1 2 #'user/bar user=> (defn foo [x y & args] nil) #'user/foo user=> (def bar (apply foo (iterate #(let [i (inc %)] (println i) i) 0))) 1 2 3 #'user/bar
