(import (scheme base)
        (scheme write)
        (list-error)
        (floyd))

(define (circular-list first . rest)
  (let ((head (list first)))
    (let loop ((tail head) (rest rest))
      (cond ((null? rest)
             (set-cdr! tail head)
             head)
            (else
             (set-cdr! tail (list (car rest)))
             (loop (cdr tail) (cdr rest)))))))

(define (generator->list g)
  (let loop ((xs '()))
    (let ((x (g)))
      (if (eof-object? x)
          (reverse xs)
          (loop (cons x xs))))))

(define-syntax show
  (syntax-rules ()
    ((show expr)
     (begin (write 'expr)
            (write-string " => ")
            (write expr)
            (newline)))))

(show (generator->list (floyd-generator '((1 2 3 4) (a b c d) (x y z)))))

(show (generator->list (floyd-generator '((1 2 3 4) (a b c d) (x y z å)))))

(show (generator->list (floyd-generator '((1 2 3 4) (a b c d) ()))))

(show (generator->list (floyd-generator (list '(1 2 3 4)
                                              (circular-list 'a 'b 'c)))))
(show (generator->list (floyd-generator (list (circular-list 1 2 3 4 5 6)
                                              (circular-list 'a 'b)))))