Anybody have experience writing a scripting language?

Hello, I've had two ideas for games I find pretty compelling, and both would require different custom scripting languages. Unfortunately, I don't have any formal CS education or experience with parsing or scripting languages. So, I'm feeling a bit lost and thinking it'd be a herculean effort, is that correct?

Has anyone here written their own language or DSL and have any insights, resources, or starting points to share?