[racket] stuck at operating text from file

From: Noel Welsh (noelwelsh at gmail.com)
Date: Mon Oct 25 09:08:00 EDT 2010

On Sun, Oct 24, 2010 at 11:18 AM, 김태윤 <kty1104 at gmail.com> wrote:
> #xf or #x1 works but
> (crop #x(second (string->list each))
>           #x(third (string->list each))
>           32 32
>           (bitmap "a.png")))
> it doesn't working at all

The #x syntax is used by the reader to interpret the text that
follows. By the time your code is running the reader has done its job.
Thus you cannot might code values and reader syntax. At run time you
can convert a string to number using string->number. To do the
conversion in base 16 you call it thus: (string->number string 16)

>   (define (a-tile each)
>     (crop (second (string->list each))
>           (third (string->list each))
>           32 32
>           ;(bitmap (string->path (string-append (first each) ".png"))
> doesn't work

You are missing string->list here.  It should be (list->string (first
(string->list each))), following the other examples above. This is
probably a bad design.

>           (bitmap "a.png")))


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