Problem Statement

Show one or more idiomatic ways of generating the Cartesian product of two arbitrary lists in your language. Demonstrate that your function/method correctly returns: and, in contrast: Also demonstrate, using your function/method, that the product of an empty list with any other list is empty. For extra credit, show or write a function returning the n-ary product of an arbitrary number of lists, each of arbitrary length. Your function might, for example, accept a single argument which is itself a list of lists, and return the n-ary product of those lists. Use your n-ary Cartesian product function to show the following products:

Let's start with the solution:

 (ns clojure.examples.product
	(:gen-class)
	(:require [clojure.pprint :as pp]))

(defn cart [colls]
  "Compute the cartesian product of list of lists"
  (if (empty? colls)
    '(())
    (for [more (cart (rest colls))
          x (first colls)]
      (cons x more))))


(doseq [lst [   [[1,2],[3,4]], 
                [[3,4],[1,2]], [[], [1, 2]], 
                [[1, 2], []],
                [[1776, 1789],  [7, 12], [4, 14, 23], [0, 1]],
                [[1, 2, 3], [30,], [500, 100]],
                [[1, 2, 3], [], [500, 100]]
            ]
        ]
    (println lst "=>")
    (pp/pprint (cart lst)))