Life Game Operator

The Life Game demo shows how Elzed handles multi-line expressions with ease. In the two examples below, the first expression sets up a 16 by 16 board and places a 'glider' in the lower left corner. The second expression applies the Life Game rules to the board and produces successive generations.

Any well-formed expression, regardless of the number of lines comprising it, can be processed by Elzed to create an expression-based operator.

// Call this expression to create a 16x16 board
// and place a glider in the lower left corner

global string board[ 16, 20 ];
global number b[ 16, 16 ];

x = 0; y = 0;

while ( y < 16 ) do
 x = 0;

 while ( x < 16 ) do
  b[ x++, y ] = 0;
 next

 board[ y++ ] = " ";
next

b[ 3, 3 ] = 1;
b[ 3, 5 ] = 1;
b[ 4, 4 ] = 1;
b[ 5, 4 ] = 1;
b[ 4, 5 ] = 1;


// Call this expression repeatedly
// to see successive generations

x = 0; y = 0;
neighbors = 0;

while ( y <= 15 ) do

 x = 0;

 while ( x <= 15 ) do

  neighbors = 0;

  if ( (y+1)<=15 ) then
   if ( (x-1)>=0 ) then
    if ( b[ x-1, y+1 ] >= 1 ) then
     neighbors++;
    end
   end

   if ( b[ x, y+1 ] >= 1 ) then
    neighbors++;
   end

   if ( (x+1)<=15 ) then
    if ( b[ x+1, y+1 ] >= 1 ) then
     neighbors++;
    end
   end
  end

  if ( (x-1)>=0 ) then
   if ( b[ x-1, y ] >= 1 ) then
    neighbors++;
   end
  end

  if ( (x+1)<=15 ) then
   if ( b[ x+1, y ] >= 1 ) then
    neighbors++;
   end
  end

  if ( (y-1)>=0 ) then
   if ( (x-1)>=0 ) then
    if ( b[ x-1, y-1 ] >= 1 ) then
     neighbors++;
    end
   end

   if ( b[ x, y-1 ] >= 1 ) then
    neighbors++;
   end

   if ( (x+1)<=15 ) then
    if ( b[ x+1, y-1 ] >= 1 ) then
     neighbors++;
    end
   end
  end

  if ( (b[ x, y ] == 0 ) and (neighbors == 3) ) then
   b[ x, y ] = -1;
  end

  if ( (b[ x, y ] == 1 ) and ((neighbors < 2) or (neighbors > 3)) ) then
   b[ x, y ] = 2;
  end

  x++;

 next

 y++;

next

y = 0;

while ( y <= 15 ) do

 x = 0;

 while ( x <= 15 ) do

  select( b[ x, y ] )

  case (-1):
   b[ x, y ] = 1;
   replace( board[ y ], "O", x, 1 );
   break;

  case 0:
   replace( board[ y ], " ", x, 1 );
   break;

  case 1:
   replace( board[ y ], "O", x, 1 );
   break;

  case 2:
   b[ x, y ] = 0;
   replace( board[ y ], " ", x, 1 );
   break;

  end

  x++;

 next

y++;

next