how many users make a critical mass? Off the top of my head, I’d say twenty. If a language had twenty separate users, meaning twenty users who decided on their own to use it, I’d consider it to be real. Getting there can’t be easy. I would not be surprised if it is harder to get from zero to twenty than from twenty to a thousand. The best way to get those initial twenty users is probably a trojan horse: give people an application they want, which happens to be written in the new language.