[plt-dev] Racket web page

On Tue, May 25, 2010 at 3:30 PM, Eli Barzilay <eli at barzilay.org> wrote:
> On May 25, Carl Eastlund wrote:
>> On Thu, May 20, 2010 at 4:31 PM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
>> >
>> > We'd like to have more 7-line programs for the middle slideshow, so
>> > please contribute.
>>
>> Command line tool to simulate rolling M dice with N sides each, for
>> each input of the form "MdN":
>>
>> #lang racket
>> (for ([s (current-command-line-arguments)])
>>   (match (regexp-match #px"(\\d+)d(\\d+)" s)
>>     [(list _ (app string->number m)
>>              (app string->number n))
>>      (for ([i (in-range m)])
>>        (printf "~a\n" (+ 1 (random n))))]))
>
> Does it help to use `app'?  (It shows off a feature, but an obscure
> one...)
>
> Anyway, you would obviously be too focused on the game to sum up your
> 7d20:
>
>  #lang racket
>  (for ([s (current-command-line-arguments)])
>    (match s
>      [(regexp #px"(\\d+)d(\\d+)" (list _ m n))
>       (let ([rolls (for/list ([i (in-range (string->number m))])
>                      (+ 1 (random (string->number n))))])
>         (printf "~s => ~a\n" rolls (apply + rolls)))]))

Yeah, the "app" came from an earlier stage in development when it
helped me fit in 7 lines.  I hadn't hit on this version.

None of your others fit in 7 lines.

--Carl