## Exam Check-List: Discussion on Part 10 - Func. React. Progr.

FeG
Endlosschleifenbastler
Beiträge: 182
Registriert: 6. Dez 2007 07:01

### Exam Check-List: Discussion on Part 10 - Func. React. Progr.

Hi,

finally ... here is my solution to the tenth (and last) topic of the exam check-list (-> spoiler alert...).

As Functional Reactive Programming actually isn't part of the exam and there are no slides, I blatantly copied the task-setting from the exam in 2011 -- and assume, that at least a question like 2. won't appear in the exam

Last but not least: Thank you, Andreas, for providing the check list -- it helped me a lot to recap the lecture content in-depth.

All the best,
Felix

1. Given a FRP program, explain what it does.

Code: Alles auswählen

(require frtime/animation)

(define start-time (value-now seconds))
(define elapsed (- seconds start-time))
(define circle1 (make-circle mouse-pos elapsed "blue"))
(display-shapes (list circle1))

The program moves a circle along with the mouse position; it's radius grows over time (radius = (current time - start time) in seconds).
2. Change the behavior of a FRP program in a speciﬁed way.

Let the radius be resetted on left mouse click.

Code: Alles auswählen

(define start-time
(hold (-=> left-clicks (value-now seconds))
(value-now seconds)))

(Well, that's from the exam, too and there we should explain, what the code does (so: the other way around). I hope I got it right..)
3. Draw a dataﬂow diagram describing the computational dependencies in the given program.

Code: Alles auswählen

circle position <-- elapsed <-- [value-now seconds]
^---- start-time <-- [value-now seconds]