Clojure Destructuring Examples

destructuring.clj

;; Anything you type in here will be executed 
;; immediately with the results shown on the 
;; right.

(def name ["Tom" "David" "Crinson"])


(str (nth name 2) ", "
     (nth name 0) " "
     (nth name 1))

;=> "Crinson, Tom David"

;;; VS

(let [[fname mname lname] name]
  (str lname ", " fname " " mname ))

; => "Crinson, Tom David"

;; Slurp Remainder

(def very-posh-person ["Geoffery" "Van" "Winkle" "The" "Third"])

(let [[fname mname lname & more] very-posh-person]
  (str lname ", " fname " " mname " " more))

;=> "Winkle, Geoffery Van (\"The\" \"Third\")"

;;; :as

(let [[fname mname lname :as whole] name]
  (str lname ", " fname " " mname " (" whole ")" ))

; => "Crinson, Tom David ([\"Tom\" \"David\" \"Crinson\"])"

;;; Associative destructuring

(let [{fname 0 lname 2} name]
  (str fname " " lname))

;=> "Tom Crinson"

;; Maps

(def mapname {:fname "Tom" :mname "David" :lname "Crinson"})

(let [{fname :fname lname :lname} mapname]
  (str fname " " lname))

;  => "Tom Crinson"

(let [{:keys [fname lname]} mapname]
  (str fname " " lname))
;  => "Tom Crinson"

(let [{:keys [fname lname title]} mapname]
  title)
;  => nil

(def nested-map {:title "Eternal Golden Braid" 
                 :author "Douglas Hofstadter", 
                 :chapters [{:title "Introduction: 
                             A Musico-Logical Offering"}
                            {:title "Chapter 1: 
                             The MU-puzzle"}]})

(let [{[introduction {ch1_title :title}] :chapters title :title} nested-map]
  str ch1_title)

(def funsies "DeAstruRcturSing isE fun!")

(let [{a 2 b 7 c 12 d 19} funsies]
  (str a b c d))