# [plt-scheme] Re: Permutation correct way to do it ?

On Apr 13, 2008, at 12:30 PM, Veer wrote:
>* ;;process-circle : (posn number symbol -> X) circle -> X
*>* ;;to apply function f on the fields of a-circle
*>* (define (process-circle f a-circle)
*>* (f (circle-center a-circle) (circle-radius a-circle) (circle-
*>* color a-circle)))
*
You didn't finish the design recipe here. Before you proceed,
you must demonstrate that that you can define
draw-circle in terms of process-circle
clear-circle in terms of process-circle
(and these definitions should be really short). Do so for all
abstractions.
;; ---
You can also abstract over the list-processing functions
draw-losh, clear-losh but of course, the appropriate function
already exists; see table on page 313.
-- Matthias