clojure.core/as->

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Type: macro Added: Clojure 1.5 Examples: 5 Runnable: 4

([expr name & forms])

Binds name to expr, evaluates the first form in the lexical context of that binding, then binds name to that result, repeating for each successive form, returning the result of the last form.

Examples

by phreed on 2014-10-02 ▶

(def owners [{:owner "Jimmy" :pets (ref [{:name "Rex" :type :dog} {:name "Sniffles" :type :hamster}])} {:owner "Jacky" :pets (ref [{:name "Spot" :type :mink} {:name "Puff" :type :magic-dragon}])}]) ;; This example is contrived as there are other more ;; terse ways of expressing the idea. It demonstrates ;; several of the ways to extract items from a collection. ;; Notice how the collection can be used in function or ;; parameter position. (as-> owners $ (nth $ 0) (:pets $) (deref $) ($ 1) ($ :type)) ;;=> :hamster

by Dimagog on 2015-02-03 ▶

(as-> 0 n (inc n) ; n is 0 here passed from first parameter to as-> (inc n)) ; n is 1 here passed from result of previous inc expression ;;=> 2

by jamesmacaulay on 2016-01-07 ▶

; use it in the middle of a -> pipeline to sprinkle in some flexibility (-> [10 11] (conj 12) (as-> xs (map - xs [3 2 1])) (reverse)) ; (11 9 7)

by x on 2016-03-02 . May have evaluation errors. ▶

;; when you want to use arbitrary positioning of your argument in a thread macro (as-> {:a 1 :b 2} m (update m :a + 10) (reduce (fn [s [_ v]] (+ s v)) 0 m)) ;; when you'd like an if statement in your thread (as-> {:a 1 :b 2} m (update m :a + 10) (if update-b (update m :b + 10) m))

by reborg on 2018-07-29 ▶

;; as-> with destructured binding (let [req {:host "//mysite.com" :path "/a/123" :x "15.1" :y "84.2"}] (as-> req {:keys [host path x y] :as m} (assoc m :url (str host path)) (assoc m :coord [(Double/valueOf x) (Double/valueOf y)]))) ;; {:host "//mysite.com" :path "/a/123" :x "15.1" :y "84.2" :url "//mysite.com/a/123" :coord [15.1 84.2]}

See also

• clojure.core/-> (4)
• clojure.core/->> (7)
• clojure.core/cond-> (4)
• clojure.core/cond->>
• clojure.core/some-> (0)
• clojure.core/some->>

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