I am a newbie to Clojure, so have some confusion around lexical
scoping especially when "let" is used in a recursive function call. To
be more precise, I am taking the example memoize() function used for
explaining the concept of atom at clojure.org.
Here is how it is explained:
(defn memoize [f]
(let [mem (atom {})]
(fn [& args]
(if-let [e (find @mem args)]
(val e)
(let [ret (apply f args)]
(swap! mem assoc args ret)
ret)))))
(defn fib [n]
(if (<= n 1)
n
(+ (fib (dec n)) (fib (- n 2)))))
(time (fib 35))
user=> "Elapsed time: 941.445 msecs"
(def fib (memoize fib))
(time (fib 35))
user=> "Elapsed time: 0.044 msecs"
My question is when "let" is used in this context, wouldn't it create
a fresh binding to a new atom{}? Any explanation would be highly
appreciated.
Thanks.
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