[plt-scheme] Re: world.ss - combination of keys

Thanks a lot for your explanation. I'm going to try to test the
universe !


On 31 oct, 15:35, Matthias Felleisen <matth... at ccs.neu.edu> wrote:
> Voilà, but you may also want to look at the experimental universe.ss  
> teachpack and its documentation:
>
>    http://www.ccs.neu.edu/home/matthias/107-f08/Universe/universe2.ss
>    http://www.ccs.neu.edu/home/matthias/107-f08/Universe/universe/
> index.html
>
> This will allow you to have two computers for two players (and soon N  
> for N).
>
> Also, the use of state/assignment is superfluous. The world/universe  
> is entirely functional. If you insist on using state, try use (void)  
> as the first and only world -- Matthias
>
> (define-struct jeu-mobile (gauche droit turn))
> ;; JeuMobile is (make-jeu-mobile Posn Posn GD)
> ;; GD is one of: 'gauche ou 'droit
>
> (define (changer-direction j key)
>    (let* ((jmg (jeu-mobile-gauche j))
>           (jmd (jeu-mobile-droit j))
>           (y1 (posn-y jmg))
>           (y2 (posn-y jmd)))
>      (begin
>        (cond
>          ((key=? key #\a) (set-jeu-mobile-turn! j 'gauche))
>          ((key=? key #\q) (set-jeu-mobile-turn! j 'droit))
>          ((key=? key 'up)
>           (if (symbol=? (jeu-mobile-turn j) 'droit)
>               (set-posn-y! jmd (- y2 10))
>               (set-posn-y! jmg (- y1 10))))
>          ((key=? key 'down)
>           (if (symbol=? (jeu-mobile-turn j) 'droit)
>               (set-posn-y! jmd (+ y2 10))
>               (set-posn-y! jmg (+ y1 10)))))
>        j)))
>
> (check-expect
>   (let ([j (make-jeu-mobile (make-posn 10 20) (make-posn 30 40)  
> 'gauche)])
>     (begin
>       (changer-direction j #\a)
>       (changer-direction j 'up)))
>   (make-jeu-mobile (make-posn 10 10) (make-posn 30 40) 'gauche))
>
> (check-expect
>   (let ([j (make-jeu-mobile (make-posn 10 20) (make-posn 30 40)  
> 'droite)])
>     (begin
>       (changer-direction j #\a)
>       (changer-direction j 'down)))
>   (make-jeu-mobile (make-posn 10 30) (make-posn 30 40) 'gauche))
>
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