/*REXX program implements a simple  ASSERT  function;  the expression can be compound.  */
  a =  1                                         /*assign a value to the   A   variable.*/
  b =  -2                                        /*   "   "   "    "  "    B       "    */
gee =  7.00                                      /*   "   "   "    "  "   GEE      "    */
zee = 26                                         /*   "   "   "    "  "   ZEE      "    */

call assert (a = 1)
call assert (b > 0)
call assert (gee = 7)
call assert (zee = a  &  zee>b)
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
assert: if arg(1)=1  then return;    parse value sourceline(sigl)  with x;  say
        say '===== ASSERT failure in REXX line' sigl", the statement is:";  say '====='  x
        say;       return