programming languages - How contains? in Clojure work? -

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• test whether list contains specific value in clojure 17 answers

i came across snippet of code in book of clojure. can please explain me how contains? works?

(contains? [1 2 3] 3) ;= false (contains? [1 2 3] 2) ;= true (contains? [1 2 3] 0) ;= true 

just @ documentation:

contains?

(contains? coll key)

returns true if key present in given collection, otherwise returns false. note numerically indexed collections vectors , java arrays, tests if numeric key within range of indexes. 'contains?' operates constant or logarithmic time; not perform linear search value. see 'some'.

so, in example, (contains? [1 2 3] 3) returns false because collection [1 2 3] not contain item @ index 3 (that means (get [1 2 3] 3) return nil).