Conway's game of life in Lua

gol.lua

ROWS = 16
COLS = 32

--- @param b table
local function zeroBoard(b)
	for i = 1, ROWS do
		b[i] = {}
		for j = 1, COLS do
			-- 0 is truthy. this is annoying.
			b[i][j] = false
		end
	end
end

--- @param b table
local function randomBoard(b)
	for i = 1, ROWS do
		b[i] = {}
		for j = 1, COLS do
			if math.random(0, 1) == 1 then
				b[i][j] = true
			else
				b[i][j] = false
			end
		end
	end
end

--- Thanks Tsoding, 1-based indexing made this harder
--- @param cx number
--- @param cy number
--- @param b table
--- @return number
local function count_nbors(cx, cy, b)
	local nbors = 0
	for dx = -1, 1 do
		for dy = -1, 1 do
			if dx ~= 0 or dy ~= 0 then
				local x = ((cx + dx) % ROWS)
				local y = ((cy + dy) % COLS)
				if x ~= 0 and y ~= 0 and b[x][y] then
					nbors = nbors + 1
				end
			end
		end
	end
	return nbors
end

--- @param b table
local function print_board(b)
	for x = 1, ROWS do
		for y = 1, COLS do
			io.write(b[x][y] and "#" or ".")
		end
		io.write("\n")
	end
end

--- @param b table
--- @return table
local function next(b)
	local nb = {}
	zeroBoard(nb)
	for x = 1, ROWS do
		for y = 1, COLS do
			local nbors = count_nbors(x, y, b)
			nb[x][y] = b[x][y] and (nbors == 2 or nbors == 3) or nbors == 3
		end
	end
	return nb
end

local b = {}
randomBoard(b)
-- zeroBoard(b)

b[3][2] = true
b[3][3] = true
b[3][4] = true
b[2][4] = true
b[1][3] = true

b[7][6] = true
b[7][7] = true
b[7][8] = true

for _ = 1, math.huge do
	os.execute("clear")
	print_board(b)
	b = next(b)
	local r = io.read("*l")
	if r == "end" then
		break
	elseif r == "reset" then
		randomBoard(b)
	end
end