This message is being posted to various lists to inform members of the Scheme
community on the development of R7RS.
I am pleased to announce that the sixth draft version of R7RS ("small"
language) has been completed by working group 1 and is now available at the
following URL:
http://trac.sac
One of my favorites is the Halloween logo you get on October 31.
On Tue, Feb 14, 2012 at 2:10 AM, Ashok Baktha wrote:
>
> No you are not hallucinating. I got the same heart based logo when using Dr
> Racket.
>
> That is pretty cool! Thanks!
>
>
>
> On 14-Feb-2012, at 12:33, Rüdiger Asche wrote:
>
> > (define default (gensym))
> > (define (default? x) (equal? x default))
>
> (Using `eq?' here is a common idiom.)
>
ah, of course, thanks for the reminder.
>
> In any case, the real point here is not the macro -- it's the
> existence of a special `none' value that marks an unsupplied value.
On Tue, Feb 14, 2012 at 17:45, Chongkai Zhu wrote:
> I simply use
>
> (define (bar . x)
> (apply foo 5 x))
>
Yes, but that does not work if the specified optional argument is not the
first one (and not the last one).
That works if all default arguments are all keyword-based though (using
keywor
On 2/11/2012 10:55 AM, Laurent wrote:
Hi,
Often I'd like to make a wrapper for a given function that has default
values (possibly with keywords).
So if I want my function to have the same default values for one
particular optional argument, I need to redefine it myself.
For example, suppose
On 2/11/2012 10:55 AM, Laurent wrote:
Hi,
Often I'd like to make a wrapper for a given function that has default
values (possibly with keywords).
So if I want my function to have the same default values for one
particular optional argument, I need to redefine it myself.
For example, suppose
On Feb 14, 2012, at 12:18 AM, Erik Silkensen wrote:
> Another option is you could turn change your fib function to be 'mk-fib' that
> returns a new instance of the fib function each time it's called:
>
> (define (mk-fib)
> (let ([n0 -1] [n1 1])
>(lambda ()
> (let ([next (+ n0 n1)])
>
On Feb 13, 2012, at 11:52 PM, Joe Gilray wrote:
> This function works, but is not "recallable" (is there a better word?). In
> other words I cannot do the following:
>
> (define f1 fib)
> (define f2 fib)
> (f1) (f1) (f2) ...
>
> and have f1 and f2 be separate fibonacci lists.
This is the imp
On Feb 14, 2012, at 12:51 AM, Erik Silkensen wrote:
> Instead of calling fib-less-than-n recursively, you could add a loop inside,
> for example something like,
>
> (define (fib-less-than-n n)
> (define fib (mk-fib))
> (let loop ([vs '()])
> (let ([fib-val (fib)])
> (if (>= fib-va
Sure, sounds good.
The (let loop ([vs '()]) ...) is a 'named let'
(http://docs.racket-lang.org/guide/let.html?q=named%20let#(part._.Named_let))
which as the guide says is equivalent to (letrec ([loop (lambda (vs) ...)])
(loop '()) --- so 'loop' is a recursive function that we're using to iterat
It has just told me that google.com is down, but it isn't.
Regards
_John Sampson_
On 13/02/2012 23:13, Neil Van Dyke wrote:
BTW, this is useful site to know about:
http://downforeveryoneorjustme.com/
Racket Users list:
http://lists.racket-lang.org/users
Thanks Danny,
Now I can use the original recursive formulation:
; function to use the fib-stream to generate a list of all fibs < n
(define (fib-stream-less-than-n n)
(let ([fib-val (stream-first fib-stream)])
(if (>= fib-val n) '() (cons fib-val (fib-less-than-n n)
I've learned a lot
Thanks Erik. Very nice! Although I miss the recursion.
please help me understand how this works, especially (let loop ([vs '()]).
What exactly is going on there?
Thanks again,
-joe
On Mon, Feb 13, 2012 at 9:51 PM, Erik Silkensen wrote:
> Instead of calling fib-less-than-n recursively, you cou
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