dynamic scoping in Lua

dynamic.lua

-- Code was taken from http://leafo.net/guides/dynamic-scoping-in-lua.html
function dynamic(name)
	local level = 2
	-- iterate over
	while true do
		if not debug.getinfo(level) then
			-- check that we didn't leave the call-stack
			break
		end
		local i = 1
		-- iterate over each local by index
		local found, found_val
		while true do
			local local_name, local_val = debug.getlocal(level, i)
			if not local_name then break end
			if local_name == name then
				-- save last found value of variable in `found_val`
				found = true
				found_val = local_val
			end
			i = i + 1
		end
		if found then
			return found_val
		end
		level = level + 1
	end
end

local function generator (...)
	local a = 100
	return function ()
		print("Lexical: ", a)
		print("Dynamic: ", dynamic("a"))
	end
end

local function runner(call, a)
	local a = 200
	call(a)
end

print(_VERSION)
runner(generator(), 400)
--[[
Lua 5.1
Lexical: 	100
Dynamic: 	200
]]