The project was created by Alexander Kahl as a pet for learning Common Lisp, is implemented almost purely functional and currently lacks documentation but the author still hopes it serves useful to someone.
To demonstrate what this is good for:
CL-USER> (cl-factoradic:dump-string-permutations "foo") foo foo ofo oof ofo oof NIL CL-USER> (coerce (cl-factoradic:factoradic-permutation (coerce "foo" 'list) 3) 'string) "OOF"
For the rest, please use your imagination.