Add common lisp version of random-string and add extension to the racket version

random-string.cl

+#!/usr/bin/env clisp
+; vim: filetype=lisp
+; random-string [length]
+
+(defvar *charset* "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
+
+(defun select-random-item (seq)
+  (elt seq (random (length seq)
+                   ;; create a newly randomly seeded random state
+                   (make-random-state t))))
+
+(defun random-string (&optional (len 16))
+  (map 'string
+       (lambda (x) (select-random-item *charset*))
+       (make-string len)))
+
+(format t (if *args*
+            (random-string (parse-integer (first *args*)))
+            (random-string)))