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1.3.0 permalink

1.2.0
1.3.0

when-first

clojure.core

(when-first bindings & body)

bindings => x xs

Same as (when (seq xs) (let [x (first xs)] body))

1 Example top

link | changes
```
user=> (when-first [a [1 2 3]] a)
1
user=> (when-first [a []] a)
nil
user=> (when-first [a nil] a)
nil
```
user=> (when-first [a [1 2 3]] a) 1 user=> (when-first [a []] a) nil user=> (when-first [a nil] a) nil

Source clojure/core.clj:4050 top

(defmacro when-first
  "bindings => x xs

  Same as (when (seq xs) (let [x (first xs)] body))"
  {:added "1.0"}
  [bindings & body]
  (assert-args when-first
     (vector? bindings) "a vector for its binding"
     (= 2 (count bindings)) "exactly 2 forms in binding vector")
  (let [[x xs] bindings]
    `(when (seq ~xs)
       (let [~x (first ~xs)]
         ~@body))))

Vars in clojure.core/when-first:

Used in 0 other vars

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Clojure Core

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when-first

clojure.core

1 Example top

See Also top

Source clojure/core.clj:4050 top

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