Destructuring Examples

Destructuring Examples.clj

;;; All Kinds of Destructuring ;;;

(let [foo 1] foo) 
; => 1

(let [[foo bar] [1 2 3]] [foo bar]) 
; => [1 2]

(let [[foo bar & baz] [1 2 3]] [foo bar baz])
; => [1 2 (3)]

(let [h {:a 1, :b 2, :c 3, :d 4}] [(keys h) (vals h)])
; => [(:d :c :b :a) (4 3 2 1)]

;; d is the whole input collection [1 2 3 4]
(let [[a b c :as d] [1 2 3 4]] d)
; => [1 2 3 4]

(let [[a b c :as d] [1 2 3 4]] [a b c])
; => [1 2 3]

;; via chouser.
(let [[a :as [b :as [c & [d]]]] [1 2]] [a b c d])
; => [1 1 1 2]

(let [{:keys [foo bar] :or {foo 5}} {:bar 2}] [foo bar])
; => [5 2]

(let [{:keys [foo bar] :or {foo 5}} (list :bar 2)] [foo bar])
; => [5 2]

(let [[& xs] [1 2 3]] xs)
; => (1 2 3)

(let [[x & xs] [1 2 3 4 5]] xs)
; => (2 3 4 5)

(let [{a :a, b :b} {:a 1, :b 2} 
      [x y] [3 4]] 
  [a b x y])
; => [1 2 3 4]