Clojure Functions

; Use fn to create new functions. A funtion always returns its last statement.

(fn [] “Hello World”) ; => fn

; (You need extra parens to call it)

((fn [] “Hello World”)) ; => “Hello World”

; You can create a var using def

(def x 1)

x ; => 1

; Assign a function to a var

(def hello-world (fn [] “Hello World”))

(hello-world) ; => “Hello World”)

; You can shorten this process by using defn

(defn hello-world [] “Hellow World”)

; The [] is the list of arguments for the function.

(den hello [name]

(str) “Hello ” name)) 

(hello “Steve”) ; => “Hello Steve”

; You can also use this shorthand to create functions:

(def hello2 #(str “Hello “ %1))

(hello2 “Fanny”) ; => “Hello Fanny”

; You can have multi-variadic functions, too

(defn hello3

  ([] “Hello World”)

  ([name] (str “Hello “ name))

(hello3 “Jake”) ; => “Hello Jake”

(hello3) ; => “Hello World”

; Functions can packextra arguments up in a seq for you

(defn hello-count [name & args]

    (str “Hellow “ name “, you passed “ (count args) “ extra args”))

(hello-count “Jamie” 1 2 3 4 5)
; => "Hello Jamie, you passed 5 extra args"