[racket] confused beginner

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On Sat, Oct 4, 2014 at 4:16 PM, Andrew Ulrich <andrewsotheraccount at gmail.com
> wrote:

> That was the problem, thanks Robby!  I guess ubuntu's apt repo's not up to
> date or something.
>
> Andrew
>
> On Sat, Oct 4, 2014 at 2:38 PM, Robby Findler <robby at eecs.northwestern.edu
> > wrote:
>
>> Are you sure you have a recent version of racket? I wonder if you're
>> looking at the docs for the latest release (on docs.racket-lang.org)
>> but you have an older release where you're trying things out.
>>
>> Note that you can look at your local docs and those docs should match
>> up to your local installation.
>>
>> Robby
>>
>>
>> On Sat, Oct 4, 2014 at 2:32 PM, Andrew Ulrich
>> <andrewsotheraccount at gmail.com> wrote:
>> > Ok, I'm stuck again:
>> > I'm trying to use place-image, but it keeps saying
>> > place-images: unbound identifier in module in: place-images
>> >
>> > It doesn't even seem to work with the example code in the docs found at:
>> >
>> http://docs.racket-lang.org/teachpack/2htdpimage.html?q=overlay#%28def._%28%28lib._2htdp%2Fimage..rkt%29._place-images%29%29
>> >
>> > Here's what I think the docs say the code is:
>> > #lang racket
>> > (require 2htdp/universe)
>> > (require 2htdp/image)
>> > (require lang/posn)
>> > (place-images
>> >    (list (circle 4 "solid" "blue")
>> >          (circle 4 "solid" "white")
>> >          (circle 4 "solid" "white")
>> >          (circle 4 "solid" "white"))
>> >    (list (make-posn 18 20)
>> >          (make-posn 0 6)
>> >          (make-posn 14 2)
>> >          (make-posn 8 14))
>> >    (rectangle 24 24 "solid" "goldenrod"))
>> >
>> > But like I said, I get the error.  I'm trying to use place-images to
>> place a
>> > bunch of sprite images on a scene for a simple video game.  I'm assuming
>> > place-images the best way to do that.
>> >
>> > Thanks in advance for helping me out.  I know it's basic stuff.
>> >
>> > On Sat, Oct 4, 2014 at 9:04 AM, Andrew Ulrich
>> > <andrewsotheraccount at gmail.com> wrote:
>> >>
>> >> Aha, great! Thanks guys!
>> >>
>> >> Andrew
>> >>
>> >> On Sat, Oct 4, 2014 at 8:54 AM, Jens Axel Søgaard <
>> jensaxel at soegaard.net>
>> >> wrote:
>> >>>
>> >>> Hi Andrew,
>> >>>
>> >>> To add what Matthias say, if you need a "function version" of bitmap,
>> >>> you can use bitmap/file instead.
>> >>>
>> >>>     (require 2htdp/image)
>> >>>     (define path-stringy "images/some.png")
>> >>>     (bitmap/file path-stringy)
>> >>>
>> >>> Note that I changed (path-stringy) to path-stringy.
>> >>>
>> >>> /Jens Axel
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> 2014-10-04 15:48 GMT+02:00 Matthias Felleisen <matthias at ccs.neu.edu>:
>> >>> >
>> >>> > What you used is called a "computed string" that is, you expect
>> bitmap
>> >>> > to evaluate the argument path-stringy to a string.
>> >>> >
>> >>> > But, in BSL, bitmap expects to be handed a literal string constant
>> (or
>> >>> > a module path):
>> >>> >
>> >>> >
>> ---------------------------------------------------------------------
>> >>> > (require 2htdp/image)
>> >>> >
>> >>> > ;; with a module path
>> >>> > (bitmap 2htdp/planetcute/character-cat-girl.png)
>> >>> >
>> >>> > ;; with a fixed string
>> >>> > (bitmap
>> >>> >
>> "plt/pkgs/htdp-pkgs/htdp-lib/2htdp/planetcute/character-cat-girl.png")
>> >>> >
>> ---------------------------------------------------------------------
>> >>> >
>> >>> > Both of these will succeed and retrieve the cat girl from the Planet
>> >>> > Cute collection that comes with Racket -- Matthias
>> >>> >
>> >>> >
>> >>> >
>> >>> >
>> >>> > On Oct 4, 2014, at 9:36 AM, Andrew Ulrich wrote:
>> >>> >
>> >>> >> Hi, I've got a really simple problem, I think.  Why is it that
>> when I
>> >>> >> try to do the following:
>> >>> >>
>> >>> >> (require 2htdp/image)
>> >>> >> (define path-stringy "images/some.png")
>> >>> >> (bitmap (path-stringy))
>> >>> >>
>> >>> >> I get the following error:
>> >>> >>  bitmap: expected the argument to specify a local path (via a
>> string)
>> >>> >> or a module path (e.g. `icons/b-run.png') in: (bitmap
>> (path-stringy))
>> >>> >>
>> >>> >> I mean, shouldn't path-stringy evaluate to a string before it's
>> passed
>> >>> >> into bitmap?  If not, then how do I use bitmap for anything
>> dynamic?
>> >>> >>
>> >>> >> Thanks,
>> >>> >> Andrew
>> >>> >> ____________________
>> >>> >>  Racket Users list:
>> >>> >>  http://lists.racket-lang.org/users
>> >>> >
>> >>> >
>> >>> > ____________________
>> >>> >   Racket Users list:
>> >>> >   http://lists.racket-lang.org/users
>> >>>
>> >>>
>> >>>
>> >>> --
>> >>> --
>> >>> Jens Axel Søgaard
>> >>
>> >>
>> >
>> >
>> > ____________________
>> >   Racket Users list:
>> >   http://lists.racket-lang.org/users
>> >
>>
>
>
> ____________________
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>   http://lists.racket-lang.org/users
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