;; reset-first-n-pixels: vector number color -> side effect, changing vector

;; Set the first n pixels in the vector to the specified color

(define reset-first-n-pixels

   (lambda (line n color)

     (cond

       ((<= n 0) 'return-whatever-we-are-done)

       (else (begin

               (vector-set! line (sub1 n) color)

               ; The sub1 allows for zero-based indexing

               (reset-first-n-pixels line (sub1 n) color))))))

Monday, December 6, 2004 -- 6:57 AM