$($define WIDTH $600)$

$($define HEIGHT $400)$

$($define DOT$-$SIZE $10)$

$($define INITIAL$-$LOCATION $($make$-$posn $(/$ WIDTH $2)(/$ HEIGHT $2)))$

$($define DOT$-$IMAGE $($circle DOT$-$SIZE "solid" "white"$))$

$($define$-$struct posn $($x y$))$ error: "posn: this name was defined in the language or a required library and cannot be re$-$defined"

$($define INITIAL$-$WORLD $($make$-$posn $(/$ WIDTH $2)(/$ HEIGHT $2)))$

;; handle$-$mouse: Posn $->$ Posn

;; Updates the dot's location to the mouse's location when clicked.

$($define $($handle$-$mouse pos$)$

$...)$

;; draw$-$dot: Posn $->$ Image

;; Draws the dot at the specified location.

$($define $($draw$-$dot pos$)$

$...)$

;; Exerddot: None $->$ None

;; Starts up the big bang program for the dot$-$moving game.

$($define $($exerddot$)$

$($big$-$bang INITIAL$-$WORLD

$($on$-$mouse handle$-$mouse$)$

$($to$-$draw draw$-$dot$)))$

;; handle$-$mouse: Posn $->$ Posn

;; Updates the dot's location to the mouse's location when clicked.

$($define $($handle$-$mouse pos$)$

pos$)$ ; For now, just return the mouse position

;; draw$-$dot: Posn $->$ Image

;; Draws the dot at the specified location.

$($define $($draw$-$dot pos$)$

$($place$-$image DOT$-$IMAGE $($posn$-$x pos$)($posn$-$y pos$)($empty$-$scene WIDTH HEIGHT$)))$