partition.clj

(defn partition-2
  ([n col]
   (partition-2 n col [] []))
  ([n col result current-partition]
   (let [element (first col)]
     (if (empty? col)
       result
       (recur n
              (rest col)
              (if (or (empty? (rest col)) (= (count current-partition) n))
                (conj result current-partition)
                result)
              (if (= (count current-partition) n)
               []
               (conj current-partition element)))))))