Your base case must be a list (Contracts and tests are optional):
#lang racket
;; -----------------------------------------------------------------------------
;; a simple fizzbuzz function
(provide
(contract-out
;; given a natural number, produce the fizz/buzz list for it
(fizzbuzz (-> natural-number/c (listof (or/c number? symbol?))))))
(module+ test
(require rackunit))
(define (printer num)
(cond((and (= 0 (remainder num 3)) (= 0 (remainder num 5))) 'fizzbuzz)
((= 0 (remainder num 3)) 'fizz)
((= 0 (remainder num 5)) 'buzz)
(else num)))
(define (fizzbuzz limit)
(define (helper current limit)
(cond ((>= current limit) (list (printer limit)))
(else (cons (printer current) (helper (+ 1 current) limit)))))
(helper 1 limit))
(module+ test
(require (submod ".."))
(check-equal? (fizzbuzz 10) '(1 2 fizz 4 buzz fizz 7 8 fizz buzz)))
If you write down 'contracts' (even informally) they may help you formulate
what to produce. If you're insecure, express contracts within the language.
On Apr 28, 2013, at 2:23 PM, Leonard Cuff wrote:
> I'm trying to teach myself scheme (racket) and decided to try writing
> fizzbuzz. My program mostly works, but instead of getting a single list, I
> get a list with a dot before the last list item, which I assume means I've
> got a 'cons' at the end rather than just one list. What am I doing wrong?
> Any general comments on style or approach also welcome.
>
> Thanks,
>
> Leonard
>
> #lang racket
>
>
> (define (printer num)
> (cond((and (= 0 (remainder num 3)) (= 0 (remainder num 5))) 'fizzbuzz)
> ((= 0 (remainder num 3)) 'fizz)
> ((= 0 (remainder num 5)) 'buzz)
> (else num)))
>
> (define (fizzbuzz limit)
> (define (helper current limit)
> (cond ((>= current limit) (printer limit))
> (else (cons (printer current)
> (helper (+ 1 current) limit)))))
> (helper 1 limit))
>
> (fizzbuzz 10)
>
> '(1 2 fizz 4 buzz fizz 7 8 fizz . buzz)
> >
> ____________________
> Racket Users list:
> http://lists.racket-lang.org/users
____________________
Racket Users list:
http://lists.racket-lang.org/users
