clojure.core/every?

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

([pred coll])

Returns true if (pred x) is logical true for every x in coll, else false.

Examples

by dpritchett on 2010-07-14 ▶

(every? even? '(2 4 6)) true (every? even? '(1 2 3)) false

by shockbob on 2011-07-16 ▶

;; you can use every? with a set as the predicate to return true if ;; every member of a collection is in the set (every? #{1 2} [1 2 3]) false (every? #{1 2} [1 2]) true ;; or use a hash-map as the predicate with every? to return true ;; if every member of a collection is a key within the map (every? {1 "one" 2 "two"} [1 2]) true (every? {1 "one" 2 "two"} [1 2 3]) false

by dkvasnicka on 2012-12-27 ▶

;; this is kind of weird IMO... but it works that way (the same for vectors) ;; See: https://en.wikipedia.org/wiki/Vacuous_truth (every? true? '()) true (every? false? '()) true ;; and similarly (every? map? '()) true (every? vector? '()) true (every? string? '()) true (every? number? '()) true ;; and even (every? :foo nil) true ;; As such a better description of every? would be ;; Returns false if there exists a value x in coll ;; such that (pred? x) is false, else true."

by chbrown on 2017-11-30 . May have evaluation errors. ▶

;; every? can replace clojure.set/subset? if and only if ;; the sets do not contain false / nil values (subset? #{1} #{1 2}) ;;=> true (every? #{1 2} #{1} ) ;;=> true ✔ (subset? #{1 3} #{1 2}) ;;=> false (every? #{1 2} #{1 3}) ;;=> false ✔ ;; however, invoking a set with a value returns the matched element, ;; causing the comparison below to fail (subset? #{true false} #{true false}) ;;=> true (every? #{true false} #{true false}) ;;=> false ✘ 😦

See also

• clojure.core/some (15)
• clojure.core/not-any?
• clojure.core/not-every?

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