Adaptation of the "Conway's Really Simple Game" code from Jack Diederich's talk "Stop Writing Classes".

stop_writing_classes_game_of_life.py

# stop_writing_classes_game_of_life.py
"""
Adaptation of the "Conway's Really Simple Game" code
from Jack Diederich's talk "Stop Writing Classes".

Meant to help make some of the logic more explicit.
"""
from itertools import chain


def neighbors(point):
    x, y = point
    return ((x - 1, y - 1), (x - 1, y), (x - 1, y + 1),
            (x, y - 1), (x, y + 1),
            (x + 1, y - 1), (x + 1, y), (x + 1, y + 1))


def advance(board):
    new_state = set()

    all_neighbors = (neighbors(point) for point in board)
    points_to_recalculate = board | set(chain(*all_neighbors))

    for point in points_to_recalculate:
        count = sum(neighbor in board for neighbor in neighbors(point))

        if count == 3 or (count == 2 and point in board):
            new_state.add(point)

    return new_state


glider = {(0, 0), (1, 2), (2, 0), (0, 1), (0, 2)}

for _ in range(1000):
    glider = advance(glider)

print(glider)