ideally you "invent" your secret source in front of a whiteboard (if you know what i mean), and then choose the language/ecosystem that fits best for the follow

ideally you "invent" your secret source in front of a whiteboard (if you know what i mean), and then choose the language/ecosystem that fits best for the following implementation, and works with your future customers' (eco-)systems. In terms of processing power, widespread availability and available libraries, JS'ish things are a good bet already. When it comes to choose language and expressions and stuff like this, there are different "meta"-languages available today.