20091201-libsvm-model-parser.clj

(defn lazy-combine-sorted [xs ys]
  "lazily combines xs and ys and returns their union (assumes xs ys sorted)"
  (lazy-seq
   (if-let [[x & xs*] xs]
     (if-let [[y & ys*] ys]
       (cond (= x y) (cons x (lazy-combine-sorted xs* ys*))
             (< x y) (cons x (lazy-combine-sorted xs* ys))
             (> x y) (cons y (lazy-combine-sorted xs ys*)))
       xs) ; no more ys
     ys))) ; no more xs

(defn combine [xs ys]
  "combines xs and ys and returns their union"
  (lazy-combine-sorted (sort xs ys)))