Clojure quick tutorial

gistfile1.clj

;; Objective
;;   1. Learn Clojure by doing Clojure
;;
;; Pre-requisites
;;   You need to have a running Clojure REPL
;;   see:    http://clojure.org/getting_started

; Hello World in Clojure
(println "Hello World")


; Declaring a variable
(def x 1)


; Arithmetic
(+ 2 5)


; Arithmetic using already-defined variables
(+ x 10)


; Arithmetic with multiple parameters
(* 2 3 4 5)


; Defining a function
(defn add-two [num]
  (+ 2 num))


; Applying a function
; note: in Lisp, the function you are applying goes first in the parentheses
(add-two 10)


; Defining a vector
(def numbers [1 2 3 4 5])


; Getting a value from a vector by index
; note: you can treat a vector as if it is a "function" mapping an index to values
(numbers 2)


; Getting the first few values from a collection
(take 3 numbers)


; reversing a sequence
(reverse numbers)


; Applying a function to all values in a collection
; Note that "map" is a "higher order function" since it takes a function as its first parameter
(map add-two numbers)


; Applying a function of two parameters function to all values in two collection
(map * numbers numbers)


; Applying an anonymous function to all values in a collection
(map #(+ % 100) numbers)


; Function that generates a function
; Note this is a "higher order function"
(defn make-adder [n]
  (fn [x]
    (+ x n)))


; Applying a generated function
((make-adder 7) 10)

nice, very nice....