Functional Conway's Game of Life (python 2.7)

conway.py

from __future__ import print_function

M = 5
N = 10
w = [
    [0,1,0,1,1,0,0,1,0,1],
    [0,1,0,1,1,0,0,1,0,1],
    [0,1,0,1,1,0,0,1,0,1],
    [0,1,0,1,1,0,0,1,0,1],
    [0,1,0,1,1,0,0,1,0,1],
]

def get(w, i, j):
    return 0 if i < 0 or j < 0 or i >= M or j >= N else w[i][j]

def neighbors(w, i, j):
    return sum(get(w, ii, jj) for ii in xrange(i-1, i+2) for jj in xrange(j-1, j+2) if ii != i or jj != j)

def cell_nextgen(w, i, j):
    n = neighbors(w, i, j)
    return 1 if n == 3 else get(w, i, j) if n == 2 else 0

def nextgen(w):
    return [[cell_nextgen(w, i, j) for j in xrange(N)] for i in xrange(M)]

def pprint(w):
    map(print, w)

def conway(w, g):
    print(' --- {} --- '.format(g))
    pprint(w)
    n = nextgen(w)
    return g if n == w else conway(n, g+1)

conway(w, 0)

This is a followup after the Global Day of Code Retreat 2015.
Time: 45 minutes
Ruleset: Functional style

• No loops
• No mutation
• Only declarations and return statements
• No side effects (other than I/O)