generating a combination of points

directions.clj

; (points-from-x-and-ys 1 [1 0 -1]) # => [[1 1] [1 0] [1 -1]]
(defn points-from-x-and-ys [x ys]
  (loop [ysleft ys results []]
    (if (empty? ysleft)
      results
      (recur 
        (rest ysleft)
        (conj results (point/create x (first ysleft)))))))

; generate a list of all possible points that can be moved given a set of possible x's and y's
(defn directions [xs ys]
  (loop [xsleft [-1 0 1] results []]
    (if (empty? xsleft)
      results
      (recur 
        (rest xsleft)
        (conj results (points-from-x-and-ys (first xsleft) ys))))))

; usage
(directions [-1 0 1] [-1 0 1])