Getting Started with Clojure - Quick Tutorial

How to run a clojure file from terminal?

 clj /tmp/my.clj

How Clojure to read from stdin?

(print (read-line))

How to pass a file through stdin to a Clojure program from terminal?

cat /tmp/input.txt | clj /tmp/my.clj

How to hello world in Clojure?

(print "hello")

How to read all lines from stdin? (assuming less than 500 lines)

(print (take-while some? (repeatedly 500 #(read-line) )))

How to define a variable? (a variable that doesn't change.. ok! a constant! )

(def n (read-line))

How to parse string in stdin to an integer?

(def n (Integer/parseInt (read-line)))

How to map a lambda function on a list?

(map count ["hello", "world"])

(map #(count %) ["hello", "world"])

How to map a lambda function on a list, and do many things with each item?

(map #(do (print "hello") (count %))  ["hello", "world"])

How to print hello 3 times?

(map println (repeat 3 "hello"))

How to get an element in a list?

(get ["hello", "world"] 1)

How to zip two lists? - concat two lists

(map vector [1 2 3] [4 5 6])

How to create a hashmap for look up?

(def lookup (zipmap [1 2 3] [4 5 6]))

How to get a value from a hashmap by key? - same as getting an element in a list

(get lookup 3)

How to define a function?

(defn add [a b] (+ a b))