I'm doing some exercises in coding that are meant for Java but I'm doing
them in Clojure. I'm stuck on this one. The goal is
to return true if an array of ints contains two consecutive 2s. I figured
I'd use Stuart Halloway's by-pairs function to turn the sequence
into pairs of numbers and check for a pair that is 2,2. This code in has22
below works if pasted into the REPL and evaluated but as a
function it always returns false. If anyone can explain my error to me it'd
be great.
( defn by-pairs [coll] (let [take-pair (fn [c]
(when (next c) (take 2 c)))]
(when-let [pair (seq (take-pair coll))]
(lazy-seq
(cons pair (by-pairs (rest coll)))))))
(defn has22 [a] (if (some true? (map #(= 2 (first %) (nth % 1))
(by-pairs [a]))) true false))
user> (some true? (map #(= 2 (first %) (nth % 1)) (by-pairs [1 2 2 2 ])))
true
user> (has22 [1 2 2 2])
false
John Holland
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