clojure.core/and

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Type: macro Added: Clojure 1.0 Examples: 4 Runnable: 3

([] [x] [x & next])

Evaluates exprs one at a time, from left to right. If a form returns logical false (nil or false), and returns that value and doesn't evaluate any of the other expressions, otherwise it returns the value of the last expr. (and) returns true.

Examples

by dakrone on 2010-10-08 ▶

(and true true) true (and true false) false (and false false) false (and '() '()) () (and '[] '[]) [] (and 0 1) ; Note that this is *not* bitwise 'and' 1 (and 1 0) 0

by jafingerhut on 2012-04-13 ▶

;; See examples for "if" explaining Clojure's idea of logical true ;; and logical false.

by Lacty on 2016-09-02 . May have evaluation errors. ▶

; Note that, and does not evaluate if the first value is false (and false nil) false (and nil false) nil (and false (println "foo")) false (and (println "foo") false) foo nil (and nil nil) nil

by Rovanion on 2017-03-24 ▶

; From the Clojure 1.9 source code. (defn qualified-keyword? "Return true if x is a keyword with a namespace" [x] (and (keyword? x) (namespace x) true)) ; Note how the return value of and is value of the last expression. (qualified-keyword? :hi/there) true ; If we instead define the function as: (defn qualified-keyword? [x] (and (keyword? x) (namespace x))) ; we get the namespace as return value: (qualified-keyword? :hi/there) "hi"

Note by huahaiy

Note add is a macro, so you cannot apply it. For example, there is a vector of some Boolean values [true true false true], which you want to test to see if they are all true. The code below will not work:

(apply add [true true false true]) ;won't work

Instead, use this:

(every? identity [true  true false true])

More discussion can be found at http://osdir.com/ml/clojure/2010-01/msg01242.html

Note by dilipd

typo: 'and' instead of 'add'?

See also

• clojure.core/or (2)
• clojure.core/if (2)
• clojure.core/every-pred (2)

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