merge

[procedure] merge less? x y

(def merge (less? x y)
  (if (no x) y
      (no y) x
      (let lup nil
        (set lup
             (fn (r x y r-x?) ; r-x? for optimization -- is r connected to x?
               (if (less? (car y) (car x))
                 (do (if r-x? (scdr r y))
                     (if (cdr y) (lup y x (cdr y) nil) (scdr y x)))
                 ; (car x) <= (car y)
                 (do (if (no r-x?) (scdr r x))
                     (if (cdr x) (lup x (cdr x) y t) (scdr x y))))))
        (if (less? (car y) (car x))
          (do (if (cdr y) (lup y x (cdr y) nil) (scdr y x))
              y)
          ; (car x) <= (car y)
          (do (if (cdr x) (lup x (cdr x) y t) (scdr x y))
              x)))))