say is a simple string key/value store for i18n or ay other case where you want namespaced strings.
Check out busted for extended examples.
local s = require("say")
s:set_namespace("en")
s:set('money', 'I have %s dollars')
s:set('wow', 'So much money!')
print(s('money', 1000)) -- I have 1000 dollars
s:set_namespace("fr") -- switch to french!
s:set('so_much_money', "Tant d'argent!")
print(s('wow')) -- Tant d'argent!
s:set_namespace("en") -- switch back to english!
print(s('wow')) -- So much money!