Please choose variable names other than Vcat and such. I like a-vcat for
example. This name emphasiszes that I get one particular vcat here -- not all
of the infinitely many possible ones.
explanation: The definition of structures introduces one more thing that is not
explained. For example,
Op 30-6-2012 15:55, Matthias Felleisen schreef:
On Jun 30, 2012, at 3:03 AM, Roelof Wobben wrote:
I can do the same for my problem.
; A Vanimal is one of :
; - (make-Vcat ( x happiness)
; (make-Vcham ( x happiness)
So Vanimal is not a struct but strictly a name.
Am I on the right track.
On Jun 30, 2012, at 3:03 AM, Roelof Wobben wrote:
> I can do the same for my problem.
>
> ; A Vanimal is one of :
> ; - (make-Vcat ( x happiness)
> ; (make-Vcham ( x happiness)
>
> So Vanimal is not a struct but strictly a name.
>
> Am I on the right track.
YES!
I think I found the solution.
I still have to design the render function.
I have this :
; niet grafische constanten.
(define lengte-werkblad 200)
(define breedte-werkblad 1000)
(define move-animal 3)
(define move-gauge 0.1)
; grafische constanten
(define kat .)
(define cham .)
(define work
Op 30-6-2012 1:38, Neil Van Dyke schreef:
Stephen Bloch wrote at 06/29/2012 06:01 PM:
Either you introduce this stuff much better than I do, or your
students are much sharper.
For the possible benefit of any students reading, I think someone say
it, rather than leave it implied: Or the differ
Stephen Bloch wrote at 06/29/2012 06:01 PM:
Either you introduce this stuff much better than I do, or your students are
much sharper.
For the possible benefit of any students reading, I think someone say
it, rather than leave it implied: Or the difference could be an isolated
effect of, say,
>
>>
> make-person ; string string number -> person
> person-forename ; person -> string
>^
>|
>+-- please do notice the semicolon here; the rest of these
> lines are comments
>
> This will ensure he gets the names right.
Interesting idea
On Jun 29, 2012, at 10:34 PM, Matthias Felleisen wrote:
>
> On Jun 29, 2012, at 5:30 PM, Stephen Bloch wrote:
>
>> This is a fairly common confusion for my students
>
>
> This is the first time I am encountering this confusion.
Really? You've never had a student write a define-struct for
On Jun 29, 2012, at 5:52 PM, Stephen Bloch wrote:
> Another thing I recommend: every time you write a define-struct, write down
> (in comments) the contracts for all the functions it gives you for free.
>
> For example,
> ; a person has a forename and a family-name (both strings), and a birth-y
Another thing I recommend: every time you write a define-struct, write down (in
comments) the contracts for all the functions it gives you for free.
For example,
; a person has a forename and a family-name (both strings), and a birth-year (a
number).
(define-struct person forename family-name bi
On Jun 29, 2012, at 5:30 PM, Stephen Bloch wrote:
> This is a fairly common confusion for my students
This is the first time I am encountering this confusion.
Racket Users list:
http://lists.racket-lang.org/users
On Jun 29, 2012, at 9:12 PM, Roelof Wobben wrote:
> As I understand it Vanimal is the world which can exist of a Vcat or a Vcham.
> The problem is that I cannot know which one it is and if don't do a
> define-struct Vanimal () I cannot check if the make the right world.
Not true. You can check
Do pay attention to Vcat? and VCham?
On Jun 29, 2012, at 4:12 PM, Roelof Wobben wrote:
> I know.
> As I understand it Vanimal is the world which can exist of a Vcat or a Vcham.
> The problem is that I cannot know which one it is and if don't do a
> define-struct Vanimal () I cannot check if th
I know.
As I understand it Vanimal is the world which can exist of a Vcat or a
Vcham.
The problem is that I cannot know which one it is and if don't do a
define-struct Vanimal () I cannot check if the make the right world.
I will reread the chapter how to solve this.
Roelof
Op 29-6-2012 21:
On Jun 29, 2012, at 3:14 PM, Roelof Wobben wrote:
> ; Te gebruiken structs
>
> ; Design a world program that works with both cats and chameleons:
> ; A VAnimal is either
> ; – a VCat
> ; – a VCham
> (define-struct Vanimal (Vchat Vcham))
Please re-read the chapter. The above is completely wrong
Thanks for the remark.
I have now this as a solution :
; niet grafische constanten.
(define lengte-werkblad 200)
(define breedte-werkblad 1000)
(define move-animal 3)
(define move-gauge 0.1)
; grafische constanten
(define kat .)
(define cham .)
(define workspace (empty-scene breedte-werkbla
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
On 27-06-12 15:56, Matthias Felleisen wrote:
>
>
> 1. You got trapped in a strange corner of the language:
>
> -- to ask whether some value is a a Vcat you should use Vcat? --
> BSL should not really allow you to say 'Vcat' all by itself.
Actually
Oke,
If I understand this the struct Vanimal is not a part of the programm ?
Roelof
Op 27-6-2012 15:56, Matthias Felleisen schreef:
1. You got trapped in a strange corner of the language:
-- to ask whether some value is a a Vcat you should use Vcat?
-- BSL should not really allow you to s
1. You got trapped in a strange corner of the language:
-- to ask whether some value is a a Vcat you should use Vcat?
-- BSL should not really allow you to say 'Vcat' all by itself.
[I need to investigate this problem. Sadly it is not a bug.]
2. Try to understand this:
(define-struct Vcat
Hello,
I try to figure out how I can check if a struct is a Vcat or a Vcham.
So i tried this:
; – a VCham
(define-struct Vanimal (animal))
; a struct has two parts ( the x-coordinate of a cat and the happiness
of the cat)
(define-struct Vcat [x happiness])
; make Vcat : number (x) number (h)
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