1 // Mandelbrot program (without character constants)

     2 

     3 val Ymin: Double = -1.3;

     4 val Ymax: Double =  1.3;

     5 val Ystep: Double = 0.05;  //0.025;

     6 

     7 val Xmin: Double = -2.1;

     8 val Xmax: Double =  1.1;

     9 val Xstep: Double = 0.02;  //0.01;

    10 

    11 val Maxiters: Int = 1000;

    12 

    13 def m_iter(m: Int, x: Double, y: Double,

    14                    zr: Double, zi: Double) : Void = {

    15   if Maxiters <= m

    16   then print_star() 

    17   else {

    18     if 4.0 <= zi*zi+zr*zr then print_space() 

    19     else m_iter(m + 1, x, y, x+zr*zr-zi*zi, 2.0*zr*zi+y) 

    20   }

    21 };

    22 

    23 def x_iter(x: Double, y: Double) : Void = {

    24   if x <= Xmax

    25   then { m_iter(0, x, y, 0.0, 0.0) ; x_iter(x + Xstep, y) }

    26   else skip()

    27 };

    28 

    29 def y_iter(y: Double) : Void = {

    30   if y <= Ymax

    31   then { x_iter(Xmin, y) ; new_line() ; y_iter(y + Ystep) }

    32   else skip() 

    33 };    

    34 

    35 

    36 y_iter(Ymin)