<html> <head> <meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body bgcolor="#FFFFFF" text="#000000"> <div class="moz-cite-prefix">Op 30-6-2012 15:55, Matthias Felleisen schreef: </div> <blockquote cite="mid:0CB0AB61-3C99-4E43-ADD5-EB70C4C1EADC@ccs.neu.edu" type="cite"> <div> <div>On Jun 30, 2012, at 3:03 AM, Roelof Wobben wrote:</div> <blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: 'Lucida Grande'; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">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. </blockquote> </div> <div> </div> <div>YES! </div> <div> </div> </blockquote> Oke, Last problem I hope. I have now 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 workspace (empty-scene breedte-werkblad lengte-werkblad)) (define gauge-omtrek (rectangle 1000 20 "outline" "black")) ; berekende constanten (define correctie-cat ( / (image-width kat)2)) (define ondergrens-cat ( - 0  correctie-cat)) (define bovengrens-cat ( + breedte-werkblad correctie-cat)) (define correctie-cham ( / (image-width cham)2)) (define ondergrens-cham ( - 0  correctie-cham)) (define bovengrens-cham ( + breedte-werkblad correctie-cham)) ; Te gebruiken structs ; Design a world program that works with both cats and chameleons: ; A VAnimal is either ; – a VCat ; – a VCham (define-struct Vcat (Xcat Hcat Richting)) ; Vcat = (make-editor Number Number) ; interp. (make-editor x h) where x is the x-coordinate of the cat and h is the happiness of the cat. ; make-editor Number Number -> Vcat ; Vcat-Xcat Editor -> Number ; Vcat-Hcat Editor -> Number ; Vcat-Richting -> String ; Vcat? Editor Any -> Boolean (define-struct Vcham (Xcham Hcham Richting)) ; Vcham = (make-editor Number Number) ; interp. (make-editor x h) where x is the x-coordinate of the cham and h is the happiness of the cham ; make-editor Number Number -> Vcat ; Vcham-Xcham Editor -> Number ; Vcham-Hcham Editor -> Number ; Vcham-Richting -> String ; Vcham? Editor Any -> Boolean ; Vcham -> Vcham ; Function who makes the image move to the left or turn to the right (check-expect (links-of-draaien-cham (make-Vcham 20 100 "left")) (make-Vcham 17 99.9 "left")) (check-expect (links-of-draaien-cham (make-Vcham -39 100 "left")) (make-Vcham -39 99.9 "right")) (check-expect (links-of-draaien-cham (make-Vcham 1037 100 "left")) (make-Vcham 1034 99.9 "left")) (define (links-of-draaien-cham s) (if ( < (Vcham-Xcham Vcham) ondergrens-cham)    (make-Vcham  (Vcham-Xcham s)  (- (Vcham-Hcham s) move-gauge) "right")    (make-Vcham (- (Vcham-Xcham s) move-animal) (- (Vcham-Hcham s) move-gauge) "left"))) ; Vcat -> Vcat ; Function who makes the image move to the left or turn to the right (check-expect (links-of-draaien-cat (make-Vcat 20 100 "left")) (make-Vcat 17 99.9 "left")) (check-expect (links-of-draaien-cat (make-Vcat -39 100 "left")) (make-Vcat -39 99.9 "right")) (check-expect (links-of-draaien-cat (make-Vcat 1037 100 "left")) (make-Vcat 1034 99.9 "left")) (define (links-of-draaien-cat s) (if ( < (Vcat-Xcat Vcat) ondergrens-cat)    (make-Vcat  (Vcat-Xcat s)  (- (Vcat-Hcat s) move-gauge) "right")    (make-Vcat (- (Vcat-Xcat s) move-animal) (- (Vcat-Hcat s) move-gauge) "left")) ) ; Vcham -> Vcham ; Function who makes the image move to the right or turn to the left (check-expect (rechts-of-draaien-cham (make-Vcham 20 100 "right")) (make-Vcham 23 99.9 "right")) (check-expect (rechts-of-draaien-cham (make-Vcham -39 100 "right")) (make-Vcham -36 99.9 "right")) (check-expect (rechts-of-draaien-cham (make-Vcham 1040 100 "right")) (make-Vcham 1040 99.9 "left")) (define (rechts-of-draaien-cham s) (if ( > (Vcham-Xcham Vcham) bovengrens-cham)    (make-Vcham  (Vcham-Xcham s)  (- (Vcham-Hcham s) move-gauge) "left")    (make-Vcham (+ (Vcham-Xcham s) move-animal) (- (Vcham-Hcham s) move-gauge) "right")))     ; Vcat -> Vcat ; Function who makes the image move to the right or turn to the left (check-expect (rechts-of-draaien-cat (make-Vcat 20 100 "right")) (make-Vcat 23 99.9 "right")) (check-expect (rechts-of-draaien-cat (make-Vcat -39 100 "right")) (make-Vcat -36 99.9 "right")) (check-expect (rechts-of-draaien-cat (make-Vcat 1040 100 "right")) (make-Vcat 1040 99.9 "left")) (define (rechts-of-draaien-cat s) (if ( > (Vcat-Xcat Vcat) bovengrens-cat)    (make-Vcat  (Vcat-Xcat s)  (- (Vcat-Hcat s) move-gauge) "left")    (make-Vcat (+ (Vcat-Xcat s) move-animal) (- (Vcat-Hcat s) move-gauge) "right")) ) ; Vanimal -> Vanimal ; Function which change the world on clock ticks. ; On every tick the X-coordinate changes 3 pixels and the happiness decrease with 0.1.   (define (tock s)     (cond       [(Vcat? s)(if(equal? (Vcat-Richting s) "left") (links-of-draaien-cat Vcat) (rechts-of-draaien-cat Vcat))]       [(Vcham? s) (if(equal? (Vcham-Richting s) "left") (links-of-draaien-cham Vcham) (rechts-of-draaien-cat Vcham))] )) ; Vanimal -> Image ; Function who display the state of the world into a image. (check-expect (render (make-Vcat 90 100 "left")) (place-image (overlay/xy gauge-omtrek 0 0 (rectangle 1000 20 "solid" "red")) 500 10 (place-image kat 90 140 workspace))) (check-expect (render (make-Vcat 0 100 "right"))   (place-image (overlay/xy gauge-omtrek 0 0 (rectangle 1000 20 "solid" "red")) 500 10 (place-image kat 0 140 workspace))) (check-expect (render (make-Vcham 90 100 "left")) (place-image (overlay/xy gauge-omtrek 0 0 (rectangle 1000 20 "solid" "red")) 500 10 (place-image cham 90 140 workspace))) (check-expect (render (make-Vcham 0 100 "right"))   (place-image (overlay/xy gauge-omtrek 0 0 (rectangle 1000 20 "solid" "red")) 500 10 (place-image cham 0 140 workspace))) (define (render s)   [cond     [(Vcat? s)   (place-image (overlay/xy gauge-omtrek 0 0 (rectangle (* 10 (Vcat-Hcat s)) 20 "solid" "red")) 500 10 (place-image kat (Vcat-Xcat s) 140 workspace))]     [ (Vcham? s) (place-image (overlay/xy gauge-omtrek 0 0 (rectangle (* 10 (Vcham-Hcham s)) 20 "solid" "red")) 500 10 (place-image cham (Vcham-Xcham s) 140 workspace))] ]) ; VCat keyevent -> Vcat ; Function who changes the world on a key-event (check-expect (happy-cat (make-Vcat 90 10 "right")"up") (make-Vcat 90 12 "right")) (check-expect (happy-cat (make-Vcat 90 100 "left")"down") (make-Vcat 90 100 "left")) (define (happy-cat Vcat k)   (cond     [ (and (key=? k "up") (< (Vcat-Hcat Vcat) 100))   (make-Vcat (Vcat-Xcat Vcat) (+ (Vcat-Hcat Vcat)2) (Vcat-Richting Vcat))]     [ (and (key=? k "down") (< (Vcat-Hcat Vcat) 100)) (make-Vcat (Vcat-Xcat Vcat) (+ (Vcat-Hcat Vcat)5) (Vcat-Richting Vcat))]     [else Vcat]     )) ; VCham keyevent -> Vcat ; Function who changes the world on a key-event (check-expect (happy-cham (make-Vcham 90 10 "right")"up") (make-Vcham 90 12 "right")) (check-expect (happy-cham (make-Vcham 90 100 "left")"down") (make-Vcham 90 100 "left")) (define (happy-cham Vcham k)   (cond     [ (and (key=? k "up") (< (Vcat-Hcat Vcat) 100))   (make-Vcat (Vcat-Xcat Vcat) (+ (Vcat-Hcat Vcat)2) (Vcat-Richting Vcat))]     [else Vcat]     )) (define (happy s k)   (cond     [ (Vcat? s) (happy-cat s k)]     [ (Vcham? s) (happy-cham s k)]     )) (define (stop s)   (cond     [ (Vcat? s) (equal? (Vcat-Hcat s) 0)]     [  (Vcham? s) (equal? (Vcham-Hcham s) 0)]     )) (define (main s)   (cond     [(Vcat? s) (big-bang s (check-with Vcat?) (on-tick tock) (on-draw render) )]     [(Vcham? s) (big-bang s (check-with Vcham?) (on-tick tock) (on-draw render) )]     )) (main (make-Vcat 12 100 "left")) But it fails with this : Vcat-Xcat: expects a Vcat; given (make-signature ...) Vcham-Xcham: expects a Vcham; given (make-signature ...) Can it be a problem that on both I call the structure s ? Roelof </body> </html>