[racket] Weird typed racket error

From: Neil Toronto (neil.toronto at gmail.com)
Date: Sun Apr 20 00:40:11 EDT 2014

On 04/19/2014 09:43 PM, Alexander D. Knauth wrote:
> On Apr 19, 2014, at 10:44 PM, Neil Toronto <neil.toronto at gmail.com
> <mailto:neil.toronto at gmail.com>> wrote:
>> That is weird. It works in the nightly build without annotating
>> anything but `sphere3d`, and likely in the next release as well.
>> Keyword arguments haven't been all that well-supported in the past, so
>> I'd try making the arguments to sphere3d positional instead.
> Making ctr-posn and r positional arguments solved the problem:
> (: sphere3d ((Vectorof Real) Nonnegative-Real [#:color Plot-Color] ->
> renderer3d))
> (define (sphere3d ctr.posn r #:color [color "black"])
>    (let: ([ctr.x : Real (vector-x ctr.posn)]
>           [ctr.y : Real (vector-y ctr.posn)]
>           [ctr.z : Real (vector-z ctr.posn)])
>      (isosurface3d (λ: ([x : Real] [y : Real] [z : Real])
>                      (let: ([posn : (Vectorof Real) (vector x y z)])
>                        (vmag^2 (v- posn ctr.posn))))
>                    (ann (sqr r) Real)
>                    (ann (- ctr.x r) (U Real False)) (ann (+ ctr.x r) (U
> Real False))
>                    (ann (- ctr.y r) (U Real False)) (ann (+ ctr.y r) (U
> Real False))
>                    (ann (- ctr.z r) (U Real False)) (ann (+ ctr.z r) (U
> Real False))
>                    #:line-style 'transparent
>                    #:color color)))
> So is it that it can handle optional keyword arguments but not mandatory
> keyword arguments?

I think I remember something like that, yes. None of Plot's keyword 
arguments are mandatory, so that would explain the difference.

Neil ⊥

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