Haskell (haskell.org) is good for developing Domain Specific Languages (DSLs). A classic example of this are financial combinators – the linked paper led to a financial services spinout (lexifi.com) that is still going strong. There is an interesting overview of using Haskell to design DSLs. I am always willing to supervise projects in this space.
Recent domains of interest include: Smart contracts; Insurance policies; requirements capture specialised for specific domains, such as operating systems, or real-time systems; healthcare applications. These can be scoped for either Year 4 projects or Year 5 dissertations
I am always open to suggestions.