I'm interested in PLT and language design and a great way to learn these subjects could be creating my own programming language.
I think there is an niche in the AI field. Yes, you have Python, C++, Go and so on. But none of them has been designed with common IA problems in mind and often have issues in performance, facility of use and debug or lack of features.
So I wonder, what would you love to have in your language when you are writting an AI algorithm or system?