power.scm

(define (power s)
  (define (power-rec a b)
    (cond
      ((null? a) b)
      (else (power-rec (cdr a) (append (map (lambda (x) (cons (car a) x)) b) b)))))
  (map reverse (power-rec s '(()))))

(use srfi-27)
(random-source-randomize! default-random-source)
(define ps (power '(寝 る)))
(define r (filter (lambda (_) (> (random-real) 0.5)) ps))
(display r)(display "\n")
(if (= 4 (length r))
  (display "寝る冪")
  (display "寝る冪でない"))