clojure.core/identity

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Type: function Added: Clojure 1.0 Examples: 8 Runnable: 6

([x])

Returns its argument.

Examples

by dpritchett on 2010-07-14 ▶

(identity 4) 4

by cschreiner on 2010-07-15 ▶

(filter identity [1 2 3 nil 4 false true 1234]) (1 2 3 4 true 1234)

by cschreiner on 2010-07-15 ▶

(map #(%1 %2) (cycle [inc identity]) [1 2 3 4 5 6 7 8 9 10]) (2 2 4 4 6 6 8 8 10 10)

by cschreiner on 2010-07-27 . May have evaluation errors. ▶

(partition-by identity (sort "abcdaabccc")) ((\a \a \a) (\b \b) (\c \c \c \c) (\d))

by shockbob on 2011-07-16 ▶

(map first (partition-by identity [1 1 2 3 3 1 1 5 5])) (1 2 3 1 5)

by OnesimusUnbound on 2011-08-01 ▶

(group-by identity "abracadabra") {\a [\a \a \a \a \a], \b [\b \b], \r [\r \r], \c [\c], \d [\d]}

by protsenkovi on 2014-12-05 ▶

(map #(identity %) [1 2 3 4]) ; ~ (map (fn [x] x) [1 2 3 4]) (1 2 3 4)

by peter-kehl on 2018-10-18 . May have evaluation errors. ▶

; `identity` can serve in workarounds, because you can't pass a macro ; to a function. For example, you can't pass `and` as a parameter to `apply`: (apply and '(true 1 "yes")) ; \=> CompilerException... Can't take value of a macro... ; Instead: (every? identity '(true 1 "yes"))

Note by Jacolyte

I don't quite see the usefulness of this :P

Note by dturczanski

It's useful for example with -> macro when we eventually want to return its argument (in this case: state)

(defn example[state] (-> state update-function-1 update-function-2 identity))

Note by lancepantz

Here is another good example:

(some identity ((juxt :foo :bar) {:bar :b}))

equivalent to

 (let [map {:bar b}] (or (:foo map) (:bar map)))

### Note by tlightsky

user=> (mapcat identity [[[0 1] [1 2]] [[11 12]]])
([0 1] [1 2] [11 12])



## See also



  clojure.core/nil? (2)


  clojure.core/some? (4)


  clojure.core/constantly (3)





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Content from [the matching ClojureDocs page](https://clojuredocs.org/clojure.core/identity), with authors
credited on each contribution.