(define max-iterations 100) (define (mandelbrot c) (define (mandelbrot-inner z i) (cond ((> (magnitude z) 4.0) 'escaped) ((= i max-iterations) 'did-not-escape) (else (mandelbrot-inner (+ c (* z z)) (+ 1 i))))) (mandelbrot-inner c 0)) (do ((y -1 (+ y 0.1))) ((>= y 1)) (do ((x -2 (+ x 0.05))) ((>= x 1) (newline)) (case (mandelbrot (make-rectangular x y)) ((escaped) (display ".")) ((did-not-escape) (display "#")))))

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