/*REXX program does a list comprehension that will create N random integers, all unique.*/
parse arg n lim .                                /*obtain optional argument from the CL.*/
if   n=='' |   n==","  then   n=   1000          /*Not specified?  Then use the default.*/
if lim=='' | lim==","  then lim= 100000          /* "      "         "   "   "     "    */
lim= min(lim, 1e5)                               /*limit the random range if necessary. */
randoms=                                         /*will contain random list of integers.*/
$= .
        do j=1  for n                            /*gen a unique random integer for list.*/

             do until wordpos($, randoms)==0     /*ensure    "      "      "     "    " */
             $= random(0, lim)                   /*Not unique?  Then obtain another int.*/
             end   /*until*/                     /*100K is the maximum range for RANDOM.*/

        randoms= $ randoms                       /*add an unique random integer to list.*/
        end   /*j*/

say  words(randoms) ' unique numbers generated.' /*stick a fork in it,  we're all done. */