You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
41 lines
962 B
Clojure
41 lines
962 B
Clojure
(ns koans.07-functions
|
|
(:require [koan-engine.core :refer :all]))
|
|
|
|
(defn multiply-by-ten [n]
|
|
(* 10 n))
|
|
|
|
(defn square [n] (* n n))
|
|
|
|
(meditations
|
|
"Calling a function is like giving it a hug with parentheses"
|
|
(= 81 (square 9))
|
|
|
|
"Functions are usually defined before they are used"
|
|
(= 20 (multiply-by-ten 2))
|
|
|
|
"But they can also be defined inline"
|
|
(= 10 ((fn [n] (* 5 n)) 2))
|
|
|
|
"Or using an even shorter syntax"
|
|
(= 60 (#(* 15 %) 4))
|
|
|
|
"Even anonymous functions may take multiple arguments"
|
|
(= 15 (#(+ %1 %2 %3) 4 5 6))
|
|
|
|
"Arguments can also be skipped"
|
|
(= "AACC" (#(str "AA" %2) "bb" "CC"))
|
|
|
|
"One function can beget another"
|
|
(= 9 (((fn [] +)) 4 5))
|
|
|
|
"Functions can also take other functions as input"
|
|
(= 20 ((fn [f] (f 4 5))
|
|
*))
|
|
|
|
"Higher-order functions take function arguments"
|
|
(= 25 ( #(% 5)
|
|
(fn [n] (* n n))))
|
|
|
|
"But they are often better written using the names of functions"
|
|
(= 25 ( #(% 5) square)))
|