Re: [Jscheme-user] macro question

[Ken A. <kan...@bb...>]

You can take this one step further by writing a function producing function:

> (define (picker x)
    (lambda () (vector-ref x (.nextInt random-gen (vector-length x)))))
(lambda picker (x)...)
> (define rocks #(1 2 3 4 5))
#(1 2 3 4 5)
> (define rock (picker rocks))
(lambda picker~0 ()...)
> (rock)
3
> (rock)
2

At 06:35 AM 8/8/2003 -0400, Geoffrey Knauth wrote:
>Never mind, I guess that was a silly question.  For now I've done this:
>
>(define (pick-one v)
>  (vector-ref v (.nextInt random-gen (vector-length v))))
>
>On Friday, Aug 8, 2003, at 00:00 US/Eastern, Geoffrey Knauth wrote:
>
>>Let's say I have:
>>
>>(define (stone-size)
>>  (vector-ref stone-sizes
>>              (.nextInt random-gen (vector-length stone-sizes))))
>>(define (stone-thickness)
>>  (vector-ref stone-thicknesses
>>              (.nextInt random-gen (vector-length stone-thicknesses))))
>>(define (caulking-type)
>>  (vector-ref caulking-types
>>              (.nextInt random-gen (vector-length caulking-types))))
>>
>>Notice the repetition?  How can I use a JScheme macro to write this once?  Ignore the fact that "es" pluralizes "thickness" while "s" pluralizes "size" and "type."
>>
>>Thanks,
>>Geoffrey
>
>
>
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