ns-cheatsheet.clj

;;
;; NS CHEATSHEET
;;
;; * :require makes functions available with a namespace prefix.
;;
;; * :use makes functions available without a namespace prefix
;;   (i.e., refers functions to the current namespace).
;;
;; * :import refers Java classes to the current namespace.
;;
;; * :refer-clojure affects availability of built-in (clojure.core)
;;   functions.
;;
;; Rules of thumb:
;;
;; * Use lists to reduce repetition in namespace paths. These are
;;   equivalent:
;;
;;     (:require clojure.contrib.math clojure.contrib.seq-utils)
;;     (:require (clojure.contrib math seq-utils))
;;
;; * Use vectors for keyword options. Examples (which are equivalent):
;;
;;     (:use [clojure.contrib.math :only [sqrt]])
;;     (:use (clojure.contrib [math :only [sqrt]]))
;;

(ns foo.bar

  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
  ;; Refers clojure.contrib.math into current NS, e.g.:
  ;;   (clojure.contrib.math/sqrt 4)
  (:require (clojure.contrib math))
  
  ;; Refers math into current NS, e.g.:
  ;;   (math/sqrt 4)
  (:require (clojure.contrib [math :as math]))

  ;; Refers clojure.contrib.seq-utils and math into current NS, e.g.:
  ;;   (clojure.contrib.seq-utils/flatten [[1 2] 3])
  ;;   (math/sqrt 4)
  (:require (clojure.contrib seq-utils [math :as math]))

  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
  ;; Refers all functions from clojure.contrib.math and
  ;; clojure.contrib.seq-utils into current NS, e.g.:
  ;;   (sqrt 4)
  ;;   (flatten [[1 2] 3])
  (:use (clojure.contrib math seq-utils))
  
  ;; Refers only sqrt and flatten into current NS, e.g.:
  ;;   (sqrt 4)
  ;;   (flatten [[1 2] 3])
  (:use (clojure.contrib [math :only [sqrt]]
                         [seq-utils :only [flatten]]))

  ;; Refers all functions from clojure.contrib.math except sqrt into
  ;; current NS
  (:use [clojure.contrib.math :exclude [sqrt]])

  ;; Refers sqrt into current NS as ccm-sqrt, plus all other math
  ;; functions e.g.:
  ;;   (ccm-sqrt 4)
  ;;   (round 1.3)
  (:use [clojure.contrib.math :rename {sqrt ccm-sqrt}])

  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
  ;; Refers ArrayList and HashMap into current NS:
  (:import (java.util ArrayList HashMap))

  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

  ;; Excludes built-in print
  (:refer-clojure :exclude [print])
  
  ;; Excludes all built-ins except print
  (:refer-clojure :only [print])
  
  ;; Renames built-in print to core-print
  (:refer-clojure :rename {print core-print}))