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You're viewing version 1.2.0 of identity. The latest stable version of Clojure Core is 1.3.0.

doc source examples comments

1.2.0

1.2.0
1.3.0

identity

clojure.core

(identity x)

Returns its argument.

© Rich Hickey. All rights reserved. Eclipse Public License 1.0

6 Examples top

link | changes
```
user=> (identity 4)
4
```
user=> (identity 4) 4
link | changes
```
user=> (filter identity [1 2 3 nil 4 false true 1234])
(1 2 3 4 true 1234)
```
user=> (filter identity [1 2 3 nil 4 false true 1234]) (1 2 3 4 true 1234)
link | changes
```
user=> (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)
```
user=> (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)
link | changes
```
user=> (partition-by identity (sort "abcdaabccc"))
((\a \a \a) (\b \b) (\c \c \c \c) (\d))
```
user=> (partition-by identity (sort "abcdaabccc")) ((\a \a \a) (\b \b) (\c \c \c \c) (\d))
link | changes
```
user=> (map first (partition-by identity [1 1 2 3 3 1 1 5 5]))
(1 2 3 1 5)
```
user=> (map first (partition-by identity [1 1 2 3 3 1 1 5 5])) (1 2 3 1 5)
link | changes
```
user=> (group-by identity "abracadabra")
{\a [\a \a \a \a \a], \b [\b \b], \r [\r \r], \c [\c], \d [\d]}
```
user=> (group-by identity "abracadabra") {\a [\a \a \a \a \a], \b [\b \b], \r [\r \r], \c [\c], \d [\d]}

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See Also top

0
clojure.core/nil?
Returns true if x is nil, false otherwise.

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Source clojure/core.clj:1117 top

(defn identity
  "Returns its argument."
  {:added "1.0"}
  [x] x)

© Rich Hickey. All rights reserved. Eclipse Public License 1.0

Vars in clojure.core/identity: defn

Comments top

3 comment(s) for identity.

Jacolyte

link

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

dturczanski

link

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))

lancepantz

link

Here is another good example:

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

equivalent to

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

Here is another good example:

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

equivalent to

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

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