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Can you destructure a function parameter but still have the original available for use? The way I'm doing it now is just using a let form inside the function body, but I wondering if there was a terser way of doing it.

noahlz
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Ilia Choly
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1 Answers1

33

Seems like :as works for functions too:

with vector

(defn test [[x y :as v]]
  {:x x :y y :v v})

(test [1 2 3 4])
=>  {:x 1 :y 2 :v [1 2 3 4]}

with hash-map

(defn test2 [{x :x y :y :as m}]
    {:x x :y y :m m})

(test2 {:x 1 :y 2 :z 3})
=> {:x 1 :y 2 :m {:x 1 :y 2 :z 3}}

See this terrific blog post: http://blog.jayfields.com/2010/07/clojure-destructuring.html

Ilia Choly
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noahlz
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    I believe let, fn, defn, etc. all use the same destructuring syntax. – JohnJ Sep 25 '12 at 03:21
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    @JohnJ That's "true". I was very confused at the blog post at first because it only uses lets as examples. The difference between the let and the fn/defn is that it uses a binding form. – Daniel Kaplan Apr 02 '13 at 21:38
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    Everything what uses `let` internally can be destructured in the same way. – Adam Arold Jan 26 '14 at 00:15