How to read lines from stdin (*in*) in clojure

Question

I am writing my first clojure program, and want to read lines from stdin.

When I try this:

(doall (map #(println %) (line-seq *in*)))

Answer 1

You should probably use doseq instead of doall:

(doseq [line (line-seq (java.io.BufferedReader. *in*))] 
    (println line))

doall:

Walks through the successive nexts of the seq, retains the head and returns it, thus causing the entire seq to reside in memory at one time.

doseq:

Does not retain the head of the sequence. Returns nil.