I think a large part of that might be the language they choose. Every C++ code example in the paper feels extremely verbose to me, and I wonder to which degree that is inherently required for encoding language semantics, and to which degree it's C++ syntax being noisy.

This is not a critique of the authors, btw. Considering the breadth and depthtof various types of domain-specific knowledge that have to be "synthesized" on a project like this, developing a mastery of C++ is almost a given. So implementing things in C++ was likely the most natural approach for them. It technically also might be the most portable choice, since anyone who has LLVM installed will also have a C++ compiler.

I do wonder what it would be like if this were built upon a language with more appropriate "ergonomics" though. Maybe they can invent and implement DSL for Deegen in Deegen, haha.