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Code ;; Your own REPL! (Read Eval Print Loop) ;; We would need a little helper macro for that ;; It does what its name says - loops forever user=> (defmacro loop-forever [& body] `(loop [] ~@body (recur))) ;; Your own REPL user=> (loop-forever (println (eval (read)))) (+ 1 2) 3 ;; If you read the above code left to right (outside in) it reads LPER. ;; Inside out it reads REPL alright. ;; Sometimes it might be easier to read code outside in, just like a sequence of steps: ;; 1. Read, 2. Eval, 3. Print, 4. Loop ;; Here's how -> helps you: user=> (-> (read) (eval) (println) (loop-forever)) (+ 1 2) 3 ;; Does that read easier for you? If it does, -> is your friend! ;; To see what Clojure did behind the scenes with your -> expression: user=> (require 'clojure.walk) nil user=> (clojure.walk/macroexpand-all '(-> (read) (eval) (println) (loop-forever))) (loop* [] (println (eval (read))) (recur)) ;; You can even use ->'s cousin ->> to setup your own REPL: user=> (->> (read) (eval) (println) (while true)) (+ 1 2) 3 ;; Can you see why we can't use -> to write the above?
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1.1.2
1.1.2