gistfile1.txt

func MakeBoard(rand_seed int) [][]bool {
  rows = [][]bool(20);
  foreach row_i in 0..20 {
    row = []bool(20);
    foreach col_i in 0..20 {
      random_bool = true;
      // Implicit & causes a gen check in push. Inlining will fix.
      row.push(random_bool);
    }
    rows.push(row); // Same here.
  }
  return rows;
}

pure func CellularAutomata<r' imm, x' rw>(
  map &r'[][]bool,
  rand_seed r'int)
x'[][]bool
x'{
  num_rows = map.size();
  num_cols = map[0].size();

  new_map = [][]bool(rows);

  foreach row_i in 0..num_rows {
    row = []bool(20);
    foreach col_i in 0..num_cols {
      num_neighbors = 0;
      num_walkable_neighbors = 0;
      for neighbor_row_i in max(row_i - 1, 0)..min(row_i + 1, num_rows - 1) {
        for neighbor_col_i in max(col_i - 1, 0)..min(col_i + 1, num_cols - 1) {
          set num_neighbors = num_neighbors + 1;
          if map[neighbor_row_i][neighbor_col_i] {
            set num_walkable_neighbors = num_walkable_neighbors + 1;
          }
        }
      }
      new_walkable =
        if num_walkable_neighbors * 2 == num_neighbors {
          (rand.Next() mod 2i64) == 0i64
        } else {
          num_walkable_neighbors > num_neighbors / 2
        };
      row.push(new_walkable); // inline to elim gen
    }
    new_map.push(row);
  }

  return new_map;
}

pure func Display<r' imm, x' rw>(
  map &r'[][]bool)
x'{
  foreach row in map {
    foreach walkable in row {
      if walkable {
        print(".");
      } else {
        print("#");
      }
    }
    println("");
  }
}

exported func main() int {
  random_seed = 1337;
  board_0 = MakeBoard(random_seed);
  board_1 = CellularAutomata(&board_0, random_seed);
  board_2 = CellularAutomata(&board_1, random_seed);
  board_3 = CellularAutomata(&board_2, random_seed);
  Display(&board_3);
  return 0;
}