How to do a powerset in DrRacket?

Question

I\'m using the beginning language with list abbreviations for DrRacket and want to make a powerset recursively but cannot figure out how to do it. I currently have this much

Answer 1

Here's my implementation of power set (though I only tested it using standard Racket language, not Beginning Student):

(define (powerset lst)
  (if (null? lst)
      '(())
      (append-map (lambda (x)
                    (list x (cons (car lst) x)))
                  (powerset (cdr lst)))))

(Thanks to samth for reminding me that flatmap is called append-map in Racket!)