gistfile1.lua

table["map"] = function (tbl, func)
	local newtbl = {}
	for k, v in pairs(tbl) do
		local key, value = (func)(k, v)
		if not value then
			value = key
			key = #newtbl + 1
		end
		newtbl[key] = value
	end
	return newtbl
end

for k, v in pairs(table.map({b = "a", c = "b", a = "c"}, function (k, v) return v, tostring(k) end)) do
	print(k, v)
end